SEMS

1
SEMS

• Speaker Changyu Wu
• Adviser Quincy Wu
• Date2006/10/30

2
Overview

• Introduction
• SEMS
• SER
• How it works
• SEMS application modules
• SEMS audio modules
• SER-SEMS relation and intercommunication
• Reference

3
Introduction

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

SER
INVITE
INVITE
200 OK
200 OK
SMTP mail
RTP
IP Telephone
SEMS
SMTP server
4
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

5
How it works

• Redirecting SIP messages to SEMS
• A caller gets connected to SEMS. SER has to pass
  every SIP message concerning that call to SEMS
  through unix socket (or FIFO).
• Loading default modules
• Application modules
• provide service logic
• Audio modules
• provide codecs and file formats

6
SEMS application modules

• Voicemail
• Records voice messages and mail them to the
  callee
• ISDN Gateway
• Support calls from and to the PSTN
• Conference
• Enables many people to talk together

7
SEMS application modules (cont)

• Announcement
• Play audio file (wav file)
• Echo
• Test module echoing your voice

8
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

9
The relation between SERSEMS

• SEMS acts as UA and uses SER as SIP stack

SER
FIFO / sockets
SEMS
10
SER-SEMS intercommunication

• SER provides two functions to pass a request to
  SEMS
• t_write_req (FIFO)
• t_write_unix (sockets)

SER
FIFO / sockets
SEMS
11
SER-SEMS intercommunication (cont)

• ser.cfg request routing example

If (method INVITE) If (urisip2._at_)
if (!lookup("location"))
t_write_unix(/tmp/am_sock, conference)
break
12
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