RTMMoIP RTMMoIP

Alfredo Terzoli / Mosioua TsietsiAlfredo Terzoli / Mosioua Tsietsi

PLANPLAN

• Did you read the hand-out?Did you read the hand-out?

• A few important acronymsA few important acronyms

• A call is more than a conversation: A call is more than a conversation: signalling!signalling!

• Timeline & general organizationTimeline & general organization

A few acronyms for you A few acronyms for you to expandto expand

• PBX PBX • TDM TDM • PSTNPSTN• T1 T1 • SS7SS7• SIPSIP

SolutionsSolutions

• PBX PBX : Private Branch Exchange: Private Branch Exchange• TDM TDM : Time Division Multiplexing: Time Division Multiplexing• PSTNPSTN : Public Switched Telephone : Public Switched Telephone

NetworkNetwork• T1 T1 : Trunk (level) 1 (ok, a bit : Trunk (level) 1 (ok, a bit

strange); btw, in SA is normally E1 – 2 strange); btw, in SA is normally E1 – 2 Mbps Mbps

• SS7SS7 : Signalling System 7: Signalling System 7• SIPSIP : Session Initiation Protocol: Session Initiation Protocol

Legacy service provider Legacy service provider useuse

Asterisk

GnuGK

iLangaproxy

iLanga Core

SER

Asterisk

GnuGK

iLangaproxy

iLanga Core

SER

TDM network 1

TDM network 2

IP Network

(Typically not (Typically not the the

Internet)Internet)

Enterprise settingEnterprise setting

Asterisk

GnuGK

iLangaproxy

iLanga Core

Legacy PBXBRIPRI

PSTNBRIPRI

SIPIAXH.323MGCP

Local VoIP Endpoints

SER

Internet

VoIP signalling protocolsVoIP signalling protocols

• SIP: Session Initiation Protocol SIP: Session Initiation Protocol – IETF, IETF, Internet Engineering Task Force Internet Engineering Task Force

• H.323H.323– ITU, International Telecommunication UnionITU, International Telecommunication Union

• MGCP: Media Gateway Control Protocol - MGCP: Media Gateway Control Protocol - ITUITU

• H.248/MEGACO: H.248/MEGACO: MEdia GAteway MEdia GAteway COntrol – ITU / IETFCOntrol – ITU / IETF

SIPSIP

• In a sense the child of SMTP (Simple In a sense the child of SMTP (Simple Mail Transport Protocol) and HTTP Mail Transport Protocol) and HTTP (Hyper Text Transfer Protocol)(Hyper Text Transfer Protocol)

• Simple: Simple: – establishes the session onlyestablishes the session only– uses SDP, for the description of the uses SDP, for the description of the

sessionsession– RTP for the transport of the mediaRTP for the transport of the media

User AgentUser Agent

UAS – serverUAS – server

UAC – clientUAC – client

UAS – serverUAS – server

UAC – clientUAC – client

A simple SIP networkA simple SIP network

A SIP conversationA SIP conversation

Some experimentsSome experiments

• First, let’s get ourselves a SIP UA First, let’s get ourselves a SIP UA besides the one embedded in the besides the one embedded in the telephone:telephone:

– SJphone, SJphone, www.sjlabs.comwww.sjlabs.com (& in the (& in the software resources for this module)software resources for this module)

ExperimentsExperiments

• Experiment 1Experiment 1: let’s call directly the : let’s call directly the hardphone, using its IP addresshardphone, using its IP address

• Experiment 2Experiment 2: let’s call the hardphone via : let’s call the hardphone via iLanga, but without being part of iLanga (btw, iLanga, but without being part of iLanga (btw, this is the way the rest of the world can contact this is the way the rest of the world can contact you)you)

• Experiment 3Experiment 3: let’s join iLanga and start using : let’s join iLanga and start using the extensions and dialling out to the PSTNthe extensions and dialling out to the PSTN

Got a packet sniffer?Got a packet sniffer?

• A good idea not to get bored with A good idea not to get bored with networks is to use a packet analyzernetworks is to use a packet analyzer

• If you don’t have one already, use If you don’t have one already, use WireShark, WireShark, http://http://www.wireshark.orgwww.wireshark.org or in the or in the software resources of this modulesoftware resources of this module

The INVITE messageThe INVITE message

Rough timelineRough timeline• First week: general VoIP concepts + SIP First week: general VoIP concepts + SIP

– your work:your work: reading, playing with SIP UA, reading, playing with SIP UA, analyzing SIP and RTP packets analyzing SIP and RTP packets

• Second week: more SIP + AsteriskSecond week: more SIP + Asterisk– your work:your work: reading, experimenting with reading, experimenting with

Asterisk; thinking about a service you want to Asterisk; thinking about a service you want to createcreate

• Third week: more Asterisk, presentation of Third week: more Asterisk, presentation of your service ideayour service idea– your work: your work: reading, starting putting together reading, starting putting together

your service, your service,

Questions?Questions?