This article describes various Certificates and compliances, Bill and Acts on data privacy, Security and prevention of Robocalls as adopted by countries around the world pertaining to Interconnected VoIP providers, telecommunications services, wireless telephone companies etc
Compliance certificates by Industry types
HIPAA (Health Insurance Portability and Accountability Act)
Deals with privacy and security of personal medical records and electronic health care transaction
Applicability : If voip company handles medical information
Not allowed Voice mail transcription
Should have End-to-End Encryption
Restrict using unsecured WiFi networks to prevent Snooping
User security , strong password rules and mandatory monthly change
Secure Firmware on VoIP phones
Maintaining Call and Access Logs
SOX( Sarbanes Oxley Act of 2002)
Also known as SOX, SarbOX or Public Company Accounting Reform and Investor Protection Act
Applicability : if managing the communications operations of a regulated, publicly traded company
Retain records which include financial and other sensitive data
ways employees are provided or denied access to records or data based on their roles and responsibilities
do information audit by a trusted third party.
Retention and deletion of files such as audio files like voicemails, text messages, video clips, declared paper records, storage, and logs of communications activities
Physical and digital security controls around cloud-based VoIP applications and the networks
Privacy Related Compliance certificates
COPPA (Children’s Online Privacy Protection Act ) of 1998
prohibits deceptive marketing to children under the age of 13, or collecting personal information without disclosure to their parents.
any information is to be passed on to a third party, must be easy for the child’s guardian to review and/or protect
2011 amendment requires that the data collected was erased after a period of time,
2014 FTC issued guidelines that apps and app stores require “verifiable parental consent.”
CPNI (Customer Proprietary Network Information) in united states is the information that communication providers acquire about their subscribers. This Individually identifiable information that is created by a customer’s relationship with a provider, such as data about the frequency, duration, and timing of calls, the information on a customer’s bill, and call identifying information. This processing information is governed strictly by FCC and certification should be renewed on an annual basis
Provider can pass along that information to marketers to sell other services, as long as the customer is notified
Communications Assistance for Law Enforcement Act (CALEA) conduct electronic surveillance by imposing specific obligations on “telecommunications carriers” for assisting law enforcement, including delivering call interception and call identification functionality to the government with a minimum of interference to customer service and privacy.
Establishes requirements of organizations that process data, defines the rights of individuals to manage their data, and outlines penalties for those who violate these rights.
No personal data may be processed unless this processing is done under one of six lawful bases specified by the regulation (consent, contract, public task, vital interest, legitimate interest or legal requirement). When the processing is based on consent the data subject has the right to revoke it at any time.
Controllers must notify Supervising Authorities (SA)s of a personal data breach within 72 hours of learning of the breach.
California Consumer Privacy Act (CCPA) 2019
consumer rights relating to the access to, deletion of, and sharing of personal information that is collected by businesses.
Allows consumers to know whether their personal data is sold or disclosed , to whom .
Allows opt-out right for sales of personal information
Right to deletion – to request a business to delete any personal information about a consumer collected from that consumer
Personal Data Protection Bill (PDP) – India 2018
This bill introduces various private and sensitive protection frameworks like restriction on retention of personal data, Right to correction and erasure (such as right to be forgotten) , Prohibition and transparency of processing of personal data. It also classifies data fiduciaries including certain social media intermediaries.
The Bill amends the Information Technology Act, 2000 to delete the provisions related to compensation payable by companies for failure to protect personal data.
Other data privacy acts similar to GDPR
South Korea’s Personal Information Protection Act 2011
Brazil’s Lei Geral de Proteçao de Dados (LGPD) 2020
Privacy Amendment (Notifiable Data Breaches) to Australia’s Privacy Act 2018
Japan’s Act on Protection of Personal Information 2017
Thailand Personal Data Protection Act (PDPA) 2020
Features offered by VOIP companies for Data privacy
Access Control & Logging
Auto Data Redaction / Account Deletion policy
SIEM (Security information and event management) alerts
Information security , Encrypted Storage For Recordings & Transcripts
Disclosing all third party services that are involved in data processing too
Role Based Access Control and 2 Factor Authentication
Data Security Audits and appointing data protection officer to oversee GDPR compliance
Against Robocalls and SPIT ( SPAM over Internet Telephony)
2009 Truth in Caller ID Act
Telephone Consumer Protection Act of 1991
Implementation of Do not call registry against use of robocalls, automatic dialers, and other methods of communication
Do-Not-Call Implementation Act of 2003
if a business has an established relationship with a customer, it can continue to call them for up to 18 months. If a consumer calls the company, say, to ask for information about the product or service, the company has three months to get back to him.
if the customer asks to not receive calls, the company must stop calling, or be subject to fines.
Exemptions – Calls from a not-for-profit B organisation , informational messages as flight cancellations , Calls from sales and debt collectors etc
Personal Data Privacy and Security Act 2009
Implemented to curb identity theft and computer hacking. Sensitive personal identifiable information includes : victim’s name, social security number, home address, fingerprint/biometrics data, date of birth, and bank account numbers.
Any company that is breached must notify the affected individuals by mail, telephone, or email, and the message must include information on the company and how to get in touch with credit reporting agencies
If the breach involves government or national security , company must also contact the Secret Service within fourteen days
TRACED Act (Telephone Robocall Abuse Criminal Enforcement and Deterrence) 2019
Canadian Radio-television and Telecommunications Commission (CRTC) 2018 -32
Unlike traditional telephone connections, which are tied to a physical location, VOIP’s packet switched technology allows a particular number to be anywhere making it more difficult for it to reach localised services like emergency numbers of Public Safety Answering Points (PSAPs) . Thus FCC regulations as well as the New and Emerging Technologies 911 Improvement Act of 2008 (NET 911 Act), interconnected VoIP providers are required to provide 911 and E911 service.
Packet Capture (PCAP) is an API that captures live network packets. Besides tracking, audit and RTC visualizers, PCAP is widely used for debugging faults such as during production alarm on high failure occurrences.
Example usecase: Production alert on 503 SIP response or log entry from a gateway is not as helpful as PCAP tracking of the session ID of call across various endpoints in and out of the network to determine the point of failure.Debugging involves :
Pre-specified SIP / RTP and related protocols capture
Docker containers can be used instead of virtual machines such as VirtualBox , to isolates applications and be OS and platform independent
Makes distributed development possible and automates the deployment possible
unpause Unpause all processes within one or more containers
update Update configuration of one or more containers
wait Block until one or more containers stop, then print their exit codes
see all iamges
> docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
sipcapture/homer-cron latest fb2243f90cde 3 hours ago 476MB
sipcapture/homer-kamailio latest f159d46a22f3 3 hours ago 338MB
sipcapture/heplify latest 9f5280306809 21 hours ago 9.61MB
<none> <none> edaa5c708b3a
See all stats
> docker stats
CONTAINER ID NAME CPU % MEM USAGE / LIMIT MEM % NET I/O BLOCK I/O PIDS
f42c71741107 homer-cron 0.00% 52KiB / 994.6MiB 0.01% 2.3kB / 0B 602MB / 0B 0
0111765091ae mysql 0.04% 452.2MiB / 994.6MiB 45.46% 1.35kB / 0B 2.06GB / 49.2kB 22
Run command from within a docker instnace
docker exec -it bash
First see all processes
select a process and enter its bash
docker exec -it 0472a5127fff bash
to edit or update a file inside docker either install vim everytime u login in resh docker conainer like
apt-get install vim
or add this to dockerfile
RUN [“apt-get”, “update”] RUN [“apt-get”, “install”, “-y”, “vim”]
see if ngrep is install , if not then install and run ngrep to get sip logs isnode that docker container
apt install ngrep
ngrep -p "14795778704" -W byline -d any port 5060
docker volume – Volumes are used for persisting data generated by and used by Docker containers. docker volumes have advantages over blind mounts such as easier to backup or migrate , managed by docker APIs, can be safely shared among multiple containers etc
docker stack – Lets to manager a cluster of docker containers thorugh docker swarm can be defined via docker-compose.yml file
create Create a new service
inspect Display detailed information on one or more services
logs Fetch the logs of a service or task
ls List services
ps List the tasks of one or more services
rm Remove one or more services
rollback Revert changes to a service’s configuration
scale Scale one or multiple replicated services
update Update a service
Run docker containers
sample run command
docker run -it -d --name opensips -e ENV=dev imagename:2.2
-it flags attaches to an interactive tty in the container.
-e gives envrionment variables
-d runs it in background and prints container id
Remove docker entities
To remove all stopped containers, all dangling images, and all unused networks:
docker system prune -a
To remove all unused volumes
docker system prune --volumes
To remove all stopped containers
docker container prune
sometimes docker images keep piling with stopped congainer such as
REPOSITORY TAG IMAGE ID CREATED SIZE d1dcfe2438ae 15 minutes ago 753MB 2d353828889b 16 hours ago 910MB ...
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
0dd6698a7517 2d353828889b "/entrypoint.sh" 13 minutes ago Exited (137) 13 minutes ago hardcore_wozniak
to remove such images and their conainer , first stop and remove confainers
docker stop $(docker ps -a -q)
docker rm $(docker ps -a -q)
Terraform is used for building, changing and versioning infrastructure. Infra as Code – can run single application to datacentres via configuration files which create execution plan. It can manage low-level components such as compute instances, storage, and networking, as well as high-level components such as DNS entries, SaaS features, etc. Resource Graph – builds a graph of all your resources
tfenv can be used to manage terraform versions
> brew unlink terraform
tfenv install 0.11.14
This is used for declaring resources and descriptions of infrastructure and associated files have a .tf or .tf.json file extension Group of resources can be gathered into a module. Terraform configuration consists of a root module, where evaluation begins, along with a tree of child modules created when one module calls another.
Example : launch a single AWS EC2 instance , fle server1.tf
container orchestration platform , automating deployment, scaling, and management of containerized applications. Can deploy to cluster of computers, automating the distribution and scheduling as well
Service discovery and load balancing – gives Pods their own IP addresses and a single DNS name for a set of Pods, and can load-balance across them.
Automatic bin packing – Automatically places containers based on their resource requirements and other constraints, while not sacrificing availability. Mix critical and best-effort workloads in order to drive up utilization and save even more resources.
Storage orchestration – Automatically mount the storage system of your choice, whether from local storage, a public cloud provider such as GCP or AWS, or a network storage system such as NFS, iSCSI, Gluster, Ceph, Cinder, or Flocker.
Self-healing – Restarts containers that fail, replaces and reschedules containers when nodes die, kills containers that don’t respond to your user-defined health check, and doesn’t advertise them to clients until they are ready to serve.
Automated rollouts and rollbacks – progressively rolls out changes to your application or its configuration, while monitoring application health to ensure it doesn’t kill all your instances at the same time.
Secret and configuration management – Deploy and update secrets and application configuration without rebuilding your image and without exposing secrets in your stack configuration.
Batch execution– manage batch and CI workloads, replacing containers that fail, if desired.
Horizontal scaling – Scale application up and down with a simple command, with a UI, or automatically based on CPU usage.
Starting Kubernetes…minikube version: v1.3.0
minikube v1.3.0 on Ubuntu 18.04
Running on localhost (CPUs=2, Memory=2461MB, Disk=47990MB) …
OS release is Ubuntu 18.04.2 LTS
Preparing Kubernetes v1.15.0 on Docker 18.09.5 …
Pulling images …
Launching Kubernetes …
Done! kubectl is now configured to use "minikube"
dashboard was successfully enabled
start Starts a local kubernetes cluster
status Gets the status of a local kubernetes cluster
stop Stops a running local kubernetes cluster
delete Deletes a local kubernetes cluster
dashboard Access the kubernetes dashboard running within the minikube cluster
docker-env Sets up docker env variables; similar to ‘$(docker-machine env)’
cache Add or delete an image from the local cache.
Configuration and Management Commands:
addons Modify minikube’s kubernetes addons
config Modify minikube config
profile Profile gets or sets the current minikube profile
update-context Verify the IP address of the running cluster in kubeconfig.
Networking and Connectivity Commands:
service Gets the kubernetes URL(s) for the specified service in your local cluster
tunnel tunnel makes services of type LoadBalancer accessible on localhost
mount Mounts the specified directory into minikube
ssh Log into or run a command on a machine with SSH; similar to ‘docker-machine ssh’
kubectl Run kubectl
ssh-key Retrieve the ssh identity key path of the specified cluster
ip Retrieves the IP address of the running cluster
logs Gets the logs of the running instance, used for debugging minikube, not user code.
update-check Print current and latest version number
controls the Kubernetes cluster manager.
Basic Commands (Beginner):
create Create a resource from a file or from stdin.
expose Take a replication controller, service, deployment or pod and expose it as a new Kubernetes Service
run Run a particular image on the cluster
set Set specific features on objects
explain Documentation of resources
get Display one or many resources
edit Edit a resource on the server
delete Delete resources by filenames, stdin, resources and names, or by resources and label selector
rollout Manage the rollout of a resource
scale Set a new size for a Deployment, ReplicaSet, Replication Controller, or Job
autoscale Auto-scale a Deployment, ReplicaSet, or ReplicationController
Cluster Management Commands:
certificate Modify certificate resources.
cluster-info Display cluster info
top Display Resource (CPU/Memory/Storage) usage.
cordon Mark node as unschedulable
uncordon Mark node as schedulable
drain Drain node in preparation for maintenance
taint Update the taints on one or more nodes
Troubleshooting and Debugging Commands:
describe Show details of a specific resource or group of resources
logs Print the logs for a container in a pod
attach Attach to a running container
exec Execute a command in a container
port-forward Forward one or more local ports to a pod
proxy Run a proxy to the Kubernetes API server
cp Copy files and directories to and from containers.
auth Inspect authorization
diff Diff live version against would-be applied version
apply Apply a configuration to a resource by filename or stdin
patch Update field(s) of a resource using strategic merge patch
replace Replace a resource by filename or stdin
wait Experimental: Wait for a specific condition on one or many resources.
convert Convert config files between different API versions
kustomize Build a kustomization target from a directory or a remote url.
label Update the labels on a resource
annotate Update the annotations on a resource
completion Output shell completion code for the specified shell (bash or zsh)
api-resources Print the supported API resources on the server
api-versions Print the supported API versions on the server, in the form of “group/version”
config Modify kubeconfig files
plugin Provides utilities for interacting with plugins.
version Print the client and server version information
DevOps monitoring tools nagios
Manage Docker configs
create Create a config from a file or STDIN
inspect Display detailed information on one or more configs
ls List configs
rm Remove one or more configs
attach Attach local standard input, output, and error streams to a running container
commit Create a new image from a container’s changes
cp Copy files/folders between a container and the local filesystem
create Create a new container
diff Inspect changes to files or directories on a container’s filesystem
exec Run a command in a running container
export Export a container’s filesystem as a tar archive
inspect Display detailed information on one or more containers
kill Kill one or more running containers
logs Fetch the logs of a container
ls List containers
pause Pause all processes within one or more containers
port List port mappings or a specific mapping for the container
prune Remove all stopped containers
rename Rename a container
restart Restart one or more containers
rm Remove one or more containers
run Run a command in a new container
start Start one or more stopped containers
stats Display a live stream of container(s) resource usage statistics
stop Stop one or more running containers
top Display the running processes of a container
unpause Unpause all processes within one or more containers
update Update configuration of one or more containers
wait Block until one or more containers stop, then print their exit codes
Alternatives, Senu multi-cloud monitoring or Raygun
Aggregate logs into logstash and provide search and filtering via Elastic Search and Kibana. Can also trigger alerts or notifications on specific keyword searches in logs such as WARNING or ERRRO or call_failed. Some common alert scenarios include :
SBC and proxy gateways failures – check states of VM instance
DNS caching alerts – Domain Name System (DNS) caching, a Dynamic Host Configuration Protocol (DHCP) server, router advertisement and network boot alerts from service such as dnsmasq
Disk usage alert – setup alerts for 80% usage and trigger an alarm to either manually prune or create automatic timely archive backups. check the percentage of DISK USAGE
Mostly it is either the logs file or pcap recorder which need to be archieved in external storage.
Use logrotate – it can rotates, compresses, and mails system logs
config file for logrorate – logrotate -vf /etc/logrotate.conf
Elevated Call failure SIP 503 or Call timeout SIP 408 – high frequency of failed calls indicate an internal issue and must be followed up by smoke testing the entire system to identify any probable issue such as undetected frequent crashes of any individual component or any blacklisting by a destination endpoint etc
sudo tail -f sip.log | grep 503
sudo tail -f sip.log | grep WARNING
cron service or processed alerts –
PID TTY STAT TIME COMMAND
2 ? S 0:00 [kthreadd]
3 ? I< 0:00 \_ [rcu_gp]
4 ? I< 0:00 \_ [rcu_par_gp]
5 ? I 0:00 \_ [kworker/0:0-eve]
6 ? I< 0:00 \_ [kworker/0:0H-kb]
7 ? I 0:00 \_ [kworker/0:1-eve]
8 ? I 0:00 \_ [kworker/u4:0-nv]
9 ? I< 0:00 \_ [mm_percpu_wq]
10 ? S 0:00 \_ [ksoftirqd/0]
11 ? I 0:00 \_ [rcu_sched]
12 ? S 0:00 \_ [migration/0]
13 ? S 0:00 \_ [cpuhp/0]
14 ? S 0:00 \_ [cpuhp/1]
15 ? S 0:00 \_ [migration/1]
16 ? S 0:00 \_ [ksoftirqd/1]
17 ? I 0:00 \_ [kworker/1:0-eve]
18 ? I< 0:00 \_ [kworker/1:0H-kb]
or checks cron status
service cron status
● cron.service - Regular background program processing daemon
Loaded: loaded (/lib/systemd/system/cron.service; enabled; vendor preset: enabled)
Active: active (running) since Fri 2016-06-26 03:00:37 UTC; 1min 17s ago
Main PID: 845 (cron)
Tasks: 1 (limit: 4383)
└─845 /usr/sbin/cron -f
Jun 26 03:00:37 ip-172-31-45-21 systemd: Started Regular background program processing daemon.
Jun 26 03:00:37 ip-172-31-45-21 cron: (CRON) INFO (pidfile fd = 3)
Jun 26 03:00:37 ip-172-31-45-21 cron: (CRON) INFO (Running @reboot jobs)
restart or start cron service if required
DB connections / connection pool process – keep listening for any alerts on DB connections failure or even warnings as this can be due to too many read operations such as in DDOS and can escalate very quickly
cron zombie process checks – zombie process or defunct process is a process that has completed execution (via the exit system call) but still has an entry in the process table: it is a process in the “Terminated state”. List xombie process and kill them with pid to free up .
kill -9 <PID1>
Bulk calls checks – consult ongoing call cmd commands for application server such as For Freeswitch use
Incase of DDOS or other macious attacker IP identification block the IP
iptables -I INPUT -s y.y.y.y -j DROP
Can also use fail2ban
>apt-get update && apt-get installfail2ban
Additionally check how many dispatchers are responding on outbound gateway
opensipsctl dispatcher dump
Process control supervisor or pm2 checks – supervisor is a Linux Process Control System that allows its users to monitor and control a number of processes
ps axf | grep supervisor
> pm2 status
[PM2] Spawning PM2 daemon with pm2_home=/Users/altanai/.pm2
[PM2] PM2 Successfully daemonized
│ id │ name │ namespace │ version │ mode │ pid │ uptime │ ↺ │ status │ cpu │ mem │ user │ watching │
htop to check memeory and CPU
Health and load on the reverse proxy, load balancer as Nginx – perform a direct curl request to host to check if Nginx responds with a non 4xx / 5xx response or not
curl -v <public-fqdn-of-server>
Incase of error response , restart
Incase of updates restart ngnix config
nginx -s reload
For HTTP/SSL proxy daemon such as tiny proxy which are used for fast resposne , set the MinSpareServers, MaxSpareServers , MaxClients , MaxRequestsPerChild etc appropriately
VPN checks – restart fireealls or IPsec incase of ssues
Additionally also check ssh service
ps axf | grep sshd
restart sshd if required
SSL cert expiry checks – to keep the operations running securely and prevent and abrupt termination it is a good practise to run regular certificate expiry checks for SSL certs especially on secure HTTP endpoint like APIs , web server and also on SIP applications servers for TLS. If any expiry is due in < 10 days to trigger an alert to renew the certs
Health of Task scheduling services such as RabbitMQ, Celery Distributed Task Queue – remote debugging of these can be set up via pdb which supports setting (conditional) breakpoints and single stepping at the source line level, inspection of stack frames, source code listing, and evaluation of arbitrary Python code in the context of any stack frame.
fscli > show status UP 0 years, 0 days, 0 hours, 58 minutes, 33 seconds, 15 milliseconds, 58 microseconds FreeSWITCH (Version 1.6.20 git 987c9b9 2018-01-23 21:49:09Z 64bit) is ready 3 session(s) since startup 0 session(s) - peak 1, last 5min 1 0 session(s) per Sec out of max 30, peak 1, last 5min 1 1000 session(s) max min idle cpu 0.00/80.83 Current Stack Size/Max 240K/8192K
Programming or Syntax error in the production environment – mostly arising due to incomplete QA/testing before pushing new changes to production. Should trigger alerts for dev teams and meet with hot patches.
Many programing application development frameworks have inbuild libs for debugging , exceotion handling and reporting such as
backend service in Django
API service in Go
Distributed memory caching – redis , memcahe : Redis info shows the master -salve configuration for all the instances as well as their memeory and cpu status.
I shall be editing this post to discuss more on the process of Service Harmonization to save the Telecom Service Provider the trouble of rewriting call logic with every telecom generation evolution ie IN to SIP to Web based WebRTC phones.
The Service Harmonization Layer does the job of holding all new and legacy services while providing uniform interface to interact with access network regardless of the back-end Call program logic .
Diagrammatic depiction of roles of Service Harmonization
Service Broker Advantages of using Service Broker vs Total Migration from In to IMS Provisioning via fixed/mobile brands «service profile» in Service Broker Architecture of SDP / Service Broker Service Broker We know that a Service broker is a service abstraction layer between the network and application layer in a telecom environment. SB( Service Broker … Continue reading Service Broker Architecture for IN and IMS
As CSPs evolve their networks for LTE, the resulting networks present tremendous challenges in voice services and application delivery. Realizing this opportunity, the telecom software industry has come forward with a purpose-built network element: the Service Broker, a solution specifically designed to overcome network architecture challenges and ensure voice service delivery from any network domain to any other network domain. Service Brokers are placed between the application layer and the control layer.
Service broker is a service abstraction layer between the network and application layer in telecom environment.
SB( Service Broker ) enables us to make use of existing applications and services from Intelligent Network’s SCP ( Service control Point ) , IMS’s Application Server as well as other sources in a harmonized manner .
Call RatConsistency of Call Records and duplicated charging records at various endpoints
A VOIP/CPaaS solution is designed to accommodate the signalling and media both along with integration leads to various external endpoints such as various SIP phones ( desktop, softphones, webRTC ), telecom carriers, different VoIP networks providers, enterprise applications ( Skype, Microsoft Lync ), Trunks etc.
A sufficiently capable SIP platform should have
Audio calls ( optionally video ) service using SIP gateways
Media services (such as recording , conferencing, voicemail, and IVR )
Messaging and presence ( could be using SIP SIMPLE, SMS , messahing service from third parties)
Interconnectivity with other IP multimedia systems, VoLTE ( optional interconnection with other types of communications networks as GSM or PSTN/ISDN).
support for VoIP signalling protocols (SIP, H,323, SCCP, MGCP, IAX) and telephony signalling protocols ( ISDN/SS7, FXS/FXO, Sigtran ) either internally via pluggable modules or externally via gateways .
Performnace factors :
Security considerations :
High availability using redundant servers in standby Load balancing IPv4 and IPv6 network layer support TCP , UDP , SCTP transport layer protocol support DNS lookups and hop by hop connectvity
authentication, authorization, and accounting (AAA) Digest authentication and credentials fetched from backend Media Encryption TLS and SRTP support Topology hidding to prevent disclosing IP form internal components in via and route headers Firewalls , blacklist, filters , peak detectors to prevent Dos and Ddos attacks
The article only outlines SIP system architecture from 3 viewpoints :
Data Centers with BCP ( Business Continuity Planning ) and DR ( Disaster Recovery )
Servers and Clusters for faster and parallel calculating
Virtualization VMs to make a distributed computing environment with HA ( high availability ) and DRS ( Distributed Resource Scheduling )
Storage SAN with built-in redundancy for the resiliency of data. WORM compliant NAS for storing voice archives over a retention period.
Racks, power supplies, battery backups, cages etc.
Networking DMZs ( Demilitarized Zones) which are interfacing areas between internal servers in the green zone and outside network VLANs for segregation between tenants. Connectivity through the public Internet as well as through VPN or dedicated optical fibre network for security.
Load Balancer ( Layer 7 )
Reverse Proxies for the security of internal IPs and port
Security controls In compliance with ISO/IEC 27000 family – Information security management systems
PKI Infrastructure to manage digital certificates
Key management with HSM ( hardware security module )
truster CA ( Certificate Authority ) to issue publicly signed certificate for TLS ( Https, wss etc)
A SIP server can be moulded to take up any role based on the libraries and programs that run on it such as gateway server, call manager, load balancer etc. This in turn defines its placement in overall VoIP communication architecture. For example – stateless proxy servers are placed on the border, – application and B2BUA server at the core
A SIP gateway is an application that interfaces a SIP network to a network utilising another signalling protocol. In terms of the SIP protocol, a gateway is just a special type of user agent, where the user agent acts on behalf of another protocol rather than a human. A gateway terminates the signalling path and can also terminate the media path .
Logical SIP entities are:
User Agent Client (UAC): Initiates SIP requests ….
User Agent Server (UAS): Returns SIP responses ….
Network Servers ….
A registrar server accepts SIP REGISTER requests; all other requests receive a 501 Not Implemented response. The contact information from the request is then made available to other SIP servers within the same administrative domain, such as proxies and redirect servers. In a registration request, the To header field contains the name of the resource being registered, and the Contact header fields contain the contact or device URIs.
A SIP proxy server receives a SIP request from a user agent or another proxy and acts on behalf of the user agent in forwarding or responding to the request. Just as a router forwards IP packets at the IP layer, a SIP proxy forwards SIP messages at the application layer.
Typically proxy server ( inbound or outbound) have no media capabilities and ignore the SDP . They are mostly bypassed once dialog is established but can add a record-route .
A proxy server usually also has access to a database or a location service to aid it in processing the request (determining the next hop).
1. Stateless Proxy Server A proxy server can be either stateless or stateful. A stateless proxy server processes each SIP request or response based solely on the message contents. Once the message has been parsed, processed, and forwarded or responded to, no information (such as dialog information) about the message is stored. A stateless proxy never retransmits a message, and does not use any SIP timers
2. Stateful Proxy Server A stateful proxy server keeps track of requests and responses received in the past, and uses that information in processing future requests and responses. For example, a stateful proxy server starts a timer when a request is forwarded. If no response to the request is received within the timer period, the proxy will retransmit the request, relieving the user agent of this task.
3 . Forking Proxy Server A proxy server that receives an INVITE request, then forwards it to a number of locations at the same time, or forks the request. This forking proxy server keeps track of each of the outstanding requests and the response. This is useful if the location service or database lookup returns multiple possible locations for the called party that need to be tried.
A redirect server is a type of SIP server that responds to, but does not forward, requests. Like a proxy server, a redirect server uses a database or location service to lookup a user. The location information, however, is sent back to the caller in a redirection class response (3xx), which, after the ACK, concludes the transaction. Contact header in response indicates where request should be tried .
The heart of all call routing setup. It loads and executes scripts for call handling at runtime and maintains transaction states and dialogs for all ongoing calls . Usually the one to rewrite SIP packets adding media relay servers, NAT . Also connects external services like Accounting , CDR , stats to calls .
Media processing is usually provided by media servers in accordance to the SIP signalling. Bridges, call recording, Voicemail, audio conferencing, and interactive voice response (IVR) are commomly used. Read more about Media Architecture here
RFC 6230 Media Control Channel Framework decribes framework and protocol for application deployment where the application programming logic and media processing are distributed.
Any one such service could be a combination of many smaller services within such as Voicemail is a combitional of prompt playback, runtime controls, Dual-Tone Multi-Frequency (DTMF) collection, and media recording. RFC 6231 Interactive Voice Response (IVR) Control Package for the Media Control Channel Framework.
DTMF( Dual tone Multi Frequency )
Inband – With Inband digits are passed along just like the rest of your voice as normal audio tones with no special coding or markers using the same codec as your voice does and are generated by your phone.
Outband – Incoming stream delivers DTMF signals out-of-audio using either SIP-INFO or RFC-2833 mechanism, independently of codecs – in this case, the DTMF signals are sent separately from the actual audio stream.
TTS ( Text to Speech )
Alexa Text-to-Speech (TTS) + Amazon Polly
Ivona – multiple language text to speech converter with ssml scripts such as below
<speak><p><s><prosody rate="slow">IVONA</prosody> means highest quality speech
synthesis in various languages.</s><s>It offers both male and female radio quality voices <break/> at a
sampling rate of 22 kHz <break/> which makes the IVONA voices a
perfect tool for professional use or individual needs.</s></p></speak>
check ivona status
service ivona-tts-http status
tail -f /var/log/tts.log
SIP defines basic methods such as INVITE, ACK and BYE which can pretty much handle simple call routing with some more advanced processoes too like call forwarding/redirection, call hold with optional Music on hold, call parking, forking, barge etc.
Extending SIP headers
Newer SIP headers defined by more updated SIP RFC’s contina INFO, PRACK, PUBLISH, SUBSCRIBY, NOTIFY, MESSAGE, REFER, UPDATE. But more methods or headers can be added to baseline SIP packets for customization specific to a particular service provider. In case where a unrecognized SIP header is found on a SIP proxy which it either does not suppirt or doesnt understand, it will simply forward it to the specified endpoint.
Call routing Scripts
Interfaces for programming SIP call routing include : – Call Processing Language—SIP CPL, – Common Gateway Interface—SIP CGI, – SIP Servlets, – Java API for Integrated Networks—JAIN APIs etc .
Some known SIP stacks :
SailFin – SIP servlet container uses GlassFish open source enterprise Application Server platform (GPLv2), obsolete since merger from Sun Java to Oracle.
Mobicents – supports both JSLEE 1.1 and SIP Servlets 1.1 (GPLv2)
Cipango – extension of SIP Servlets to the Jetty HTTP Servlet engine thus compliant with both SIP Servlets 1.1 and HTTP Servlets 2.5 standards.
WeSIP – SIP and HTTP ( J2EE) converged application server build on OpenSER SIP platform
Additionally SIP stacks are supported on almost all popular SIP programming lanaguges which can be imported as lib and used for building call routing scripts to be mounted on SIP servers or endpoints such as :
PJSIP in C
Sofia in kamailio , Freswitch
Some popular SIP server also have proprietary scripting language such as – Asterisk Gateway Interface (AGI) , application interface for extending the dialplan with your functionality in the language you choose – PHP, Perl, C, Java, Unix Shell and others
media services such as conferencing, voicemail, and IVR,
messaging as IM and presence based on SIMPLE,
programmable services through standardized APIs and development of new modules
near-end and far-end NAT traversal for signalling and media flows
interconnectivity with other IP multimedia systems, VoLTE ( optional interconnection with other types of communications networks as GSM or PSTN/ISDN)
Registry, location and lookup service
Serial and parallel forking
A sufficiently capable SIP platform shoudl consist of following features :
Performance factors :
High availability using redundant servers in standby
IPv4 and IPv6 support
Security considerations :
digest authentication and credentials fetched from backend
TLS and SRTP support
Topology hiding to prevent disclosng IP form internal components in via and route headers
Firewalls , blacklist, filters , peak detectors to prevent Dos and Ddos attacks .
Collecting and Processing PCAPS
VoIP monitor – network packet sniffer with commercial frontend for SIP RTP RTCP SKINNY(SCCP) MGCP WebRTC VoIP protocols
it uses a passive network sniffer (like tcpdump or wireshark) to analyse packets in realtime and transforms all SIP calls with associated RTP streams into database CDR record which is sent over the TCP to MySQL server (remote or local). If enabled saving SIP / RTP packets the sniffer stores each VoIP call into separate files in native pcap format (to local storage).
To adapt SIP to modern IP networks with inter network traversal ICE, far and near-end NAT traversal solutions are used. Network Address traversal is crtical to traffic flow between private public network and from behind firewalls and policy controlled networks
One can use any of the VOVIDA-based STUN server, mySTUN , TurnServer, reStund , CoTURN , NATH (PJSIP NAT Helper), ReTURN, or ice4j
Near-end NAT traversal
STUN (session traversal utilities for NAT) – UA itself detect presence of a NAT and learn the public IP address and port assigned using Nating. Then it replaces device local private IP address with it in the SIP and SDP headers. Implemented via STUN, TURN, and ICE. limitations are that STUN doesnt work for symmetric NAT (single connection has a different mapping with a different/randomly generated port) and also with situations when there are multiple addresses of a end point.
TURN (traversal using relay around NAT) or STUN relay – UA learns the public IP address of the TURN server and asks it to relay incoming packets. Limitatiosn since it handled all incoming and outgong traffic, it must scale to meet traffic requirments and should not become the bottle neck junction or single point of failure.
ICE (interactive connectivity establishment) – UA gathers “candidates of communication” with priorities offered by the remote party. After this client pairs local candidates with received peer candidates and performs offer-answer negotiating by trying connectivity of all pairs, therefore maximising success. The types of candidates : – host candidate who represents clients’ IP addresses, – server reflexive candidate for the address that has been resolved from STUN – and a relayed candidate for the address which has been allocated from a TURN relay by the client.
Far-end NAT traversal
UA is not concerned about NAT at all and communicated using its local IP port. The border controller implies a NAT handling components such as an application layer gateway (ALG) or universal plug and play (UPnP) etc which resolves the private and public network address mapping by act as a back to back user agent (B2BUA). Far end NAT can also be enabled by deploying a public SIP server which performs media relay (RTP Proxy/Media proxy).
Limitations of this approach (-) security risks as they are operating in the public network (-) enabling reverse traffic from UAS to UAC behind NAT.
A keep-alive mechanism is used to keep NAT translations of communications between SIP endpoint and its serving SIP servers opened , so that this NAT translation can be reused for routing. It contains client-to-server “ping” keep-alive and corresponding server-to-client “pong” messages. The 2 keep-alive mechanisms: a CRLF keep-alive and a STUN keep-alive message exchange.
The 3 types of SIP URIs,
address of record (AOR)
fully qualified domain name (FQDN)
globally routable user agent (UA) URI
SIP uniform resource identifiers (URIs) are identified based on DNS resolution since the URI after @ symbol contains hostname , port and protocl for the next hop.
Adding record route headers for locating the correct SIP server for a SIP message can be done by : – DNS service record (DNS SRV) – naming authority pointer (NAPTR) DNS resource record
Steps for SIP endpoints locating SIP server
From SIP packet get the NAPTR record to get the protocl to be used
Inspect SRV record to fetch port to use
Inspect A/AAA record to get IPv4 or IPv6 addresses ref : RFC 3263 – Locating SIP Servers Can use BIND9 server for DNS resolution supports NAPTR/SRV, ENUM, DNSSEC, multidomains, and private trees or public trees.
CDR store call detail records along with proof of call with tiemstamps, orignation, destination, duaration, rate etc. At the end of month or any other term, the aggregated CDR are cumulatively processed to generate the bill for a user. This heavy data stream needs to be accurately processed and this can be achived by using data-pipelines like AWS kinesis or Kafka eventstore.
The prime requirnment for the system is to handle enormous amount of call records data in relatime , cater to a number of producers and consumers.
For security the data is obfuscated into blob using base 64 encoding.
For good consistency only a single shard should be rsponsible to process one user account’s bill.
Data Streams for billing service
AWSKinesis – Kinesis Data Streams is sued for for rapid and continuous data intake and aggregation. The type of data used can include IT infrastructure log data, application logs, social media, market data feeds, and web clickstream data. It supports data sharding (ie number of call records grouped) and uses a partition Key ( string MD5 hash) to determine which shard the record goes to.
(+) This system can handle high volume of data in realtime and produce call uuid specfic reults which can be consumed by consumers waiting for the processed results
(-) If not consumed with a pre-specified time duration the processed results expire and are irretrivable . Self implement publisher to store teh processed reults from kisesis stream to data stores like Redis / RDBMS or other storge locations like s3 , dynamo DB. If pieline crashes during operation , data is lost
(-) Data stream should have low latency igesting contnous data from producer and presenting data to consumer.
Call Rate and Accounting
Generally data streams proecssing are used for crtical and voluminious service usage like for – metering/billing – server activity, – website clicks, – geo-location of devices, people, and physical goods
Call Rates are very crticial for billing and charging the calls . Any updates from the customer or carriers or individuals need to propagate automatically and quickly to avoid discrpencies and neagtive margins. CDRs need to be processed sequentially and incrementally on a record-by-record basis or over sliding time windows, and used for a wide variety of analytics including correlations, aggregations, filtering, and sampling.
To acheieve this the follow setup is ideal to use the new input rate sheet values via web UI console or POST API and propagate it quickly to main DB via AWS SQS which is a queing service and AWS lamda which is a serverless trigger based system . This ensures that any new input rates are updates in realtime and maintin fallback values in s3 bucket too
It is an advantage to plan for ahead for connection with IMS such as openIMS, support for Voip signalling protocols (SIP, H,323, SCCP, MGCP, IAX) and telephony signalling protocls ( ISDN/SS7, FXS/FXO, Sigtran ) either internally via pluggable modules or externally via gateways or for SIP trunking integration via OTT providers/ cloud telephony.
Adhere to Standard
The obvious starting milestone before making a full-scale carrier-grade, SIP-based VoIP system is to start by building a PBX for intra-enterprise communication. There are readily available solutions to make an IP telephony PBX Kamailio, FreeSWITCH, asterisk, Elastix, SipXecs. It is important to use the standard protocol and widely acceptable media formats and codecs to ensure interoperability and reduce compute and delay involved in protocol or media transcoding.
Need backend , cache , databse integration to npt only store routing rules with temporary varaible values but also aNeed backend, cache, database integration to not only store routing rules with temporary variable values but also account details, call records details, access control lists etc. Should therefore extend integration with text-based DB, Redis, MySQL, PostgreSQL, OpenLDAP, and OpenRadius.
Consistency of Call Records and duplicated charging records at various endpoints
In current Voip scenarios a call may be passing thorugh various telco providers , ISP and cloud telephony serviIn current VoIP scenarios, a call may be passing through various telco providers, ISP and cloud telephony service providers where each system maintains its own call records and billing. This in my opinion is duplication and can be avoided by sharing a consistent data store possible in the blockchain. This is an experimental idea that I have further explored in this article
There are other external components to setup a VOIP solution apart from Core voice Servers and gateways like the ones listed below, I will try to either add a detailed overall architecture diagram here or write about them in an seprate article. Keep watching this space for updates
Billing and Invoice
Number Management ( DIDs ) and porting
Single Sign On and User Account Management with Oauth and SAML
To make a model that separates the services offered by
fixed-line (traditional telcos), mobile (traditional cellular), and converged service providers (cable companies and others who provide triple-play — voice, video, and data — services) from the access networks used to receive those services.
IMS architecture is broken into distinct layers:
Revenue streams for plain vanilla voice services are sharply falling and the need of the hour is to propose smart intuitive and creative service to kep up the Telecom market alive .