SEMS

Speaker: Changyu Wu

Adviser: Quincy Wu

Date:2006/11/13

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Overview

Introduction SEMS SER

How it works SEMS application modules SEMS audio modules

SER-SEMS relation and intercommunication Reference

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Introduction

SEMS(SIP express media server) is a extensible media server which helps you adding voice services to your VoIP system。

IP Telephone

SEMS SMTP server

SER

INVITE INVITE

200 OK 200 OK

RTP

SMTP

mail

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Introduction-SER

SER(SIP Express Router) is an open-source SIP proxy, redirect and registrar server.

SER’ s configuration file is divided into four main sections. Global parameter External module loading Module parameters Routing blocks

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How it works

Redirecting SIP messages to SEMS A caller gets connected to SEMS. SER has to pass ev

ery SIP message concerning that call to SEMS through unix socket (or FIFO).

IP Telephone SEMS SMTP

server

SER

INVITE INVITE

200 OK

200 OK

RTP

SMTP

mail

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SEMS-Modules

Loading default modules Application modules

provide service logic Audio modules

provide codecs and file formats

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SEMS application modules

Voicemail Records voice messages and mail them to the cal

lee ISDN Gateway

Support calls from and to the PSTN Conference

Enables many people to talk together

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SEMS application modules (cont) Announcement

Play audio file (wav file) Echo

Test module echoing your voice

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Announcement modules

IP telephone SEMS

RTP

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Conference modules

RTP

RTP

IP telephone

IP telephone

SEMS

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Voicemail modules

SEMSIP telephone SMTP server

SMTP

email

RTP

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Echo modules

IP telephone

SEMS

Re: Hello

Hello

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SEMS audio modules

Audio modules provide codecs and file formats wav: G711u, G711a, .wav file gsm: GSM 06.10 codec iLBC: iLBC internet low bitrate codec mp3: .mp3 file writer for mp3 voicemail

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The relation between SER+SEMS SEMS acts as UA and uses SER as SIP stack

SER

SEMS

FIFO / sockets

IP telephone

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SER-SEMS intercommunication SER provides two

functions to pass a request to SEMS

1. t_write_req (FIFO)

2. t_write_unix (sockets)

SER

SEMS

FIFO / sockets

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SER-SEMS intercommunication (cont) ser.cfg request routing example:

If (method == “INVITE”) {

If (uri=~”sip:2.*@”) {

if(!t_write_req(“/tmp/am_fifo”,”announcement”)) { t_reply(“500”,”error contacting sems”);

}; break;

}; }

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Reference

SEMS http://www.iptel.org/sems

SER http://www.iptel.org/ser

SIP.edu http://www.internet2.edu/sip.edu/

Regular Expressions http://www.regular-expressions.info/tutorial.html