Monthly Archives: July 2014

2nd and 3rd generation of telecommunication

Although the history of telecom evolution begins with PSTN and switches we shall oit them as they are truly legacy now .  We have seen the evolution of second to third generation of telecom most recently .  Where 2 G is referred to as the GSM era  , 2.5 G as the GPRS with GSM era . The following two diagram denote the service operators architecture nodes in both these times .

Note that in pure 2G there was only circuit switched communication services .

gsm

The advent 2.5 G bought packet switching for data access along with existing circuit switching for voice network .

gsm_gprs

Note that the processes such as billing etc had begun merging for both the circuit switched and packet switched networks .

However as the mobile became smarted and hungry for faster internet , it bbecame necessary to bring in faster speed and hence was born 3G. . Now 3G was further succeeded by 3.5G ( HSPA – High Speed Downlink Packet Access ) eventually 4G ( LTE Long Term Evolution ) as we can see now but that is another story .

Difference between WebRTC and plugin based communication

A lot of service providers ie telecom operators had deduced their own ways to provide Web based communication even before WebRTC was born . With time , as WebRTC has become stronger , more secure , resilient to failure they have come around to migrate their existing system from previous closed box native APIs to opensource WebRTC APIs.

The first figure ( given below ) depicts a communication platform build over plugins and proprietary APIs using HTTP REST based signaling .

2014-07-22_1212

Web Communication Service Architecture over HTTP/ REST API

As the migration took place the proprietary API components were replaced by Open standard based entities such as plugins were replaced by WebRTC APIs, HTTP REST based signalling was replaced by SIP ( Session Initiation Protocol ) .

Web Communication Service Architecture over WebRTC SIP

Web Communication Service Architecture over WebRTC SIP

Note telecom operator network did not had to face transformation by integration of WebRTC elements .

Interoperability between WebRTC , SIP phones and others

WebRTC SIP clients

What is the role of SIP server ?

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 .

How does WebRTC Solution traverse through FireWalls ?

NAT traversal across Firewalls is achieved via TURN/STUN through ICE candidates gathering .Current ice_servers are : stun:stun.l.google.com:19302 and  turn:user@numb.viagenie.ca

What audio and video codecs are supported by WebRTC client side alone ?

Without the role of Media Server WebRTC solution supports Opus , PCMA , PCMU for audio and VP8 for video call.

RTCBreaker if enabled provides a third party B2BUA agent that performs certain level of codec conversion to H.264, H.263, Theora or MP4V-ES for non WebRTC supported agents.

What video resolution is supported by WebRTC solution ?

The browser will try to find the best video size between max and min based on the camera capabilities.

Options are : sqcif | qcif | qvga | cif | hvga | vga | 4cif | svga | 480p | 720p | 16cif | 1080p

We can also predefine the video size such as minWidth, minHeight, maxWidth, maxHeight.

What bandwidth is required to run WebRTC solution ?

We can set maximum audio and video bandwidth to use or use the browser’s ability to set it hy default at runtime . This will change the outgoing SDP to include a “b:AS=” attribute. Browser negotiates the right value using RTCP-REMB and congestion control.

SIPML5 client by dubango

calltakenoffhold

Telestax WebRTC client

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SIPJS with flash network support

windows_IE_1

JSSIP – MIT license 2014-02-09_1444

SIP phones in Ubuntu ( Linux system)

SFL phone

linux sfl 2 linux sfl 1

Yate SIP phone

linux yate 2 linux yate 1

Linphone

ubuntulinphon4 linuxlinphone2

Windows Operating system SIP software

Xlite is well known SIP softphone for windows dessktop

xlite 1

Xlite new version

windows_xlite_7 windows_xlite_6_001 windows_xlite_6 windows_xlite_3

Kapanga SIP softphone . It is also runnable on Linux desktop through windows compatibility softwares like wine

windows_kapanga_3 windows_kapanga_2

FreeSwitch Communicator , comes along with the Freeswitch Media Server .

windows_freeswitchcomm__2 windows_freeswitch_comm_3

Boghe SIP RCS client

windows_boghe_5 windows_boghe_4 windows_boghe_2 windows_boghe_1

Jitsi SIP phone

jitsi 2 jitsi 1

MAC SIP software

idoubs desktop SIP RCS client for Mac

Screen shot 2014-06-13 at 4.03.27 PM

iOS SIP phone applications

Linphone

IMG-20140703-WA0003  IMG-20140703-WA0006 IMG-20140703-WA0007  IMG-20140710-WA0001 IMG-20140710-WA0002

Android SIP applications

Sipdroid , opensource

Screenshot_2014-07-01-19-36-47 Screenshot_2014-07-01-19-37-00 Screenshot_2014-07-01-19-37-44 Screenshot_2014-07-01-19-37-54 Screenshot_2014-07-01-19-38-46