voice mail system in internet protocol

8/6/2019 Voice Mail System in Internet Protocol

1/3

Project Title : Voice Mail System in Internet Protocol (IP) Private Branch

Exchange (PBX)

Abstract

IP PBX (shown above) is an application of VoIP (Voice over Internet Protocol)

technology. This technology is used to provide voice and video communication

using data network. IETF has defined protocols for VoIP signaling (call setup, call

teardown) and transport of media (packet containing voice samples). SIP is the most

widely used signaling protocol and RTP is the media protocol.

IP PBX is used inside a campus to provide voice and video communication. Voice

mail is one of the important features provided by an IP PBX.

When in internal or external caller calls an IP phone number, if the called party isnot answering, call will be forwarded to voice mail system. Voice message of caller

will be transported to voice mail system using RTP protocol, which in turn will use

UDP and IP protocols. Later, when called party sees a voice message indication on

his phone, he/she will enter password and listen to voice message. Voice message

of caller (stored in VM system) will be transported to called party IP phone using

RTP protocol.

IP Phone

1

IP Phone

2


2/3

Advantages of VoIP Technology:

Reduces expenses because of same data network being used for data andvoice/video communicationNew applications and services are possibleMaintenance, and training staff needed for single network

Advantage of Voice mail feature:

The person who does not answer call will come to who tried contacting him andpurpose of call. This will help him/her to return the call or suitably act on themessage.

Scope of Project

The project involves design,coding, and testing of software modules to

implement voice mail.

Design has to be carried out and a document has to be prepared and format is

shown below:

- Data structures needed for the project (RTP protocol header, RTP

message/packet)

- Library functions, Linux system calls, and socket APIs used for the project

- C functions ( and semantics) to be written by project team

- C main function ( Flowchart / semantics)

Coding of client and server modules will be done using C language. The program

will be in two source files (client.c and server.c).

Testing of client and server modules will be done using two linux computers

connected using LAN. Pre-recorded voice message (stored in vm.wav file. File will

contain a header and PCM samples) will be used. The number voice of samples

(PCM) in the message depends on duration of message recorded. Each RTPmessage will contain 160 PCM samples and N RTP messages will be sent from on

linux computer 1 to other. N RTP messages will be stored in linux computer 2.

When called user (phone 2) wants to listen to voice message, these will be

transmitted from linux computer 2 to linux computer 1. Header of .wav file will be

added and voice message will be played.


3/3

LAN

(Phone 1, Phone 2)

(Voice Mail System)

Other Details

Network Programming

RTP protocol will use UDP and IP protocols. Project uses linux socket APIs for this

purpose.

Tools used

GNU gcc compiler, ld linker, and gdb source level debugger.

Demo

Demo will be done using two Linux machines on a LAN (Setup used for testing).

Pre-recorded voice message (voice samples stored in a .wav file) will be used.

Called user (Phone 2) will be asked to enter a password and VM system will check

for correctness of the password entered and if correct, voice message will be

transported to phone 2.

Linux computer 1 Linux computer 2

voice mail system in internet protocol

Documents