Why Lua is a good choice for Scripting call configurations in SIP servers like Kamailio and Freeswitch

Programing in SIP servers enables the IP telephony provider to add complex control that is difficult to realise with simple dialplan XML and IVR menus. These are best handled by using a program that is compiled with the telecom application server and invoked by SIP requests or responses in the session. This may include using … Continue reading Why Lua is a good choice for Scripting call configurations in SIP servers like Kamailio and Freeswitch


Due to its very flexible and customisable routing engine it can be used in number of scenarios such as an SIP proxy or a router and due to its high throughput it is widely recommended as an enterprise grade inbound/outbound proxy server.

Freeswitch PBX system

IP PBX FreeSWITCH Class 4 switch Class 5 switch freeswitch-setup-as-hosted-ip-pbx Freeswitch as B2BUA This article talks about setting up an in-house hosted Enterprise PBX system for sure and private communication within enterprise communication. IP PBX A PBX acts as the central switching system for phone calls within a business. Cloud Hosted IP PBX Systems On-premise … Continue reading Freeswitch PBX system


This post describes the installation , setup and configuration of Office SIP server to provide a registrar to our SIP based WebRTC application .

BEA Weblogic SIP server

Bea server is a old SIP servlet container ie application server which is used to embed control logic in a program. 1. Install Bea Weblogic 2. Follow the Installation steps Make domain 3. Goto the installation directory . Usually C:/bea/user_projects/mydomain/ . click on startweblogic.cmd in windows. In case the system is linux run script … Continue reading BEA Weblogic SIP server

SIP Presence

We have already learned about Sip user agent and sip network server. SIP clients initiates a call and SIP server routes the call . Registrar is responsible for name resolution and user location. Sip proxy receives calls and send it to its destination or next hop. Presence is user’s reachability and willingness to communicate its … Continue reading SIP Presence

Interoperability between WebRTC, SIP phones and softphones

SIP Server convert the SIP transport from WebSocket protocol to UDP, TCP or TLS which are supported by all legacy networks. It also facilitates the use of rich serves such as phonebook synchronisation , file sharing , oauth in client .

SIP and SDP Messages Explained

SIP is a widely adopted application layer protocol used in VoIP calls and confernecing applciations and in IMS architeture or pure packet switched networks . More on SIP , its packet structure , transaction and dialogs , loose and strict record routing , location service , near and far end nating , and commonly used … Continue reading SIP and SDP Messages Explained

SIP VoIP system architecture basics

Infrastructure-requirements Integral Components of a VOIP SIP based architecture SIP Gateways Registrar Server Proxy Server  Stateless Proxy Server Stateful Proxy Server Forking Proxy Server Redirect Server Application Server Adding Media Management DTMF( Dual tone Multi Frequency ) TTS ( Text to Speech ) Developing SIP based applications Basic SIP methods Extending SIP headers Call routing … Continue reading SIP VoIP system architecture basics

SIP ( Session Initiation Protocol )

SIP – Application layer protocol SIP Requests SIP responses Session Description Protocol  (SDP) SIP transactions, dialog , branch Matching in-dialog transactions/requests Record Routing strict routing loose routing Mobility and Location Service Network Address Translator ( NAT) Far End Traversal Near End Traversal SIP Call Flows Registeration Call Redirection Forking click to Dial SIP for Instant … Continue reading SIP ( Session Initiation Protocol )

Mobicents SIP server platform

We know that SIP is in the p2p session layer of the OSI mode and used to setup voip sessions and that a SIP Servlets must be executed within a SIP Servlets Container, which implements the SIP Servlet specification. Mobicents sip servlets have been extensively used to create , deploy and manage VOIP services. Also … Continue reading Mobicents SIP server platform


A diagrammatic layout of the nodes , interwokring among them and involvment of SIP in the different planes of  IMS architecture .


SIP Servlet 1.0 API •JSR 116 •Built into the Servlet container that also hosts  portlets and HTTP Servlets. •SIP Servlet API developed under the JCP (Java Community Process) as JSR 116 (Java Specification Request), as a set of neutral interfaces Servlet Container •Environment in which a servlet can exist •Loads and initializes a servlet •Invokes … Continue reading JSR 116 – SIP SERVLET 1.0

Freeswitch Modules

This section describes some of the popular and useful freeswitch module. Although there are many more modules, I have picked a few of commonly used one and divided them into categories Logger modules in Freeswitch XML Interfaces in Freeswitch Event system and Event Handlers in Freeswitch mod_amqp mod_cdr_csv DataBase Applications Info, Intercept and eavesdrop Channel … Continue reading Freeswitch Modules

FreeSwitch SIP and Media Server

Architecture and Design of Freeswitch Core Threaded Model  State Machine in Freeswitch Core Channel Variables Dialplan Speak Time and Date on Call Call Routing based on destination number and forwarding to voice mail on no answer Call routing based on day and time Match incoming network IP address with pre configured IP Store captured values … Continue reading FreeSwitch SIP and Media Server