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Document Sample
SIP Essentials
The Session Initiation Protocol
Presented by
David Sheppard
1
2
Volvo. Get to know… Schedule
Agenda - Morning
• Session 1
– Welcome and Introductions
– General Introduction to SIP. Placing SIP in the
context of Conventional Telephony and IP Networks
• Coffee Break
• Session 2
– Basic Elements of a SIP Network
• 12.30 Lunch
3
Agenda - Afternoon
• Session 3
– Signalling and Message Flow
– SIP Methods
• Coffee Break
• Session 4
– Ubiquity Products, inc Demo
– Plenary - Questions and Answers
4
5
Human need
6
7
Basic Telecom Architecture
8
Basic Telecom Architecture
Local
exchange Local
exchange
Local
exchange
Local
Trunk exchange
Local Exchange
exchange
Connection Orientated - Switched Circuit Local
exchange
Synchronous
Local Local
Real time exchange exchange
9
Telecom Reliability?
99.999%
10
IP Network Reliability?
??.???%
11
12
Telco works well. Review IP
Basic IP Architecture
IP Network
Data Transfer
13
Converting Text to Packets
Sending text over an IP Network
Each packet individually
Addressed with the
Address of the destination
Host
14
Converting Text to Packets
Sending text over an IP Network
100111000
010110010
110110011
Out to the IP Network
15
Converting Text to Packets
Sending text over an IP Network
100111000
010110010
110110011
Out to the IP Network
16
Converting Text to Packets
Sending text over an IP Network
100111000
010110010
110110011
Out to the IP Network
17
Converting Text to Packets
Sending text over an IP Network
Out to the IP Network
18
Basic IP Architecture
IP Network
?
Packets – first come first served
Packet Switching - Connectionless
Asynchronous
Not real-time
19
20
…Packetising voice
Converting
10011000100011
Speech to
01101101001011
Packets
10111001001001 Sending Voice over an
10001100001011 IP Network
Speech – analogue wave
Converted to digital
Converted to binary
100110
0
Out to the IP Network
21
Converting
10011000100011
Speech to
01101101001011
Packets
10111001001001 Sending Voice over an
10001100001011 IP Network
Converted to binary
010001
1
Out to the IP Network
22
Converting
10011000100011
Speech to
01101101001011
Packets
10111001001001 Sending Voice over an
10001100001011 IP Network
Converted to binary
011011
0
Out to the IP Network
23
Converting
10011000100011
Speech to
01101101001011
Packets
10111001001001 Sending Voice over an
10001100001011 IP Network
Converted to binary
Out to the IP Network
24
25
Data networks can handle loss. Voice? Why bother … Voice Tolerance
VoIP Tolerances
High
Low
Loss Delay / Latency
26
27
Internet phone experience? Why bother? 2+… 3
Predicted use of VoIP
28
VoIP v. Telco Cost Ratio 1:4
Source: U. Black, VoIP Author, 1999
VoIP
Telco
0 1 2 3 4
Pound to pound comparison
29
VoIP v. Telco Cost Ratio 1:27
Source: James Crowe, CEO of Level 3
VoIP
Telco
0 10 20 30
Pound to pound comparison
30
Predicted VoIP Income Generation
Source: Gartner/Dataquest/BhawaniShanka/Voice on the Net/March 2000
$ Billion
120 “This new network will be bigger than the world’s
telephone system, more revolutionary than the
100 Internet, and have the potential to create more
80 wealth than even the PC industry” Wholesale Voice over IP
Paul Johnson of Robertson Stephens,
60 an American investment bank
Fax over IP
40 Voice over ATM
20 Voice over Frame Relay
Voice over Private/Carrier IP
0 Voice over Public Internet
7
8
9
0
1
2
3
4
9
9
9
0
0
0
0
0
9
9
9
0
0
0
0
0
1
1
1
2
2
2
2
2
31
Why is VoIP cheaper?
32
Tariff Bypassing
£
£
£
£
£
£ £
£
£
£
£
33
Tariff Bypassing
£
£
£
… short term measure.
34
Cheaper Hardware, and less of it
Local Exchange
Racks of Switches
Processors
Memory Cards
Cables
Power Supplies
Operating System
Local exchanges and Trunk Exchanges are geographically located throughout the network Software
Training
Router Router
Router
Whole network can
Router function on 1 Server
Router Network Server
Processors
Memory Cards
Router Cables
Power Supplies
Router
Router Operating System
Software
A whole network can be served by one Network Server Training
35
More Calls, Same Cost… Better Codecs
10011000100011
Each line needs
01101101001011
Out to the
64
10111001001001
G.711 Codec 10001100001011
10111001001001
kb/s PSTN Network
Voice Network
LIne 1
LIne 2
LIne 3
Better Codecs 10011000100011 5.3 kb/s Out to the
LIne 5
LIne 6
and DSPs LIne 7
LIne 8
IP Network
Many 5.3 kb/s calls in the IP Network
space of 1 64 kb/s call
36
37
… and Ad Serv
38
Others are doing it!
39
40
Why IP networks? … Issues addressed.
VoIP issues are being addressed
• Prioritising real-time packets – let them go first.
• More network processing power – faster
connections and routing
• More local processing power – SIP phones &
better Codecs & DSPs as standard in PCs
• Service providers using dedicated infrastructures
or Virtual Private Networks to guarantee
bandwidth
• Better redundancy in network equipment.
41
Telco Intelligence?
Here
At the heart of the network core
42
IP Intelligence?
Here
Here Here
Here
Here
Here
Here
Here
Here
Here Here Here Here
Here Here
“… the new “SIP” phone, which is helping to propel
Here
Here
Here this revolution along, takes control for setting up all
Here Here
the telephone services (and more) that a customer
Here
Here needs out of the hands of the carrier’s central office
Here
Here
and places it firmly in the hands of the user instead.
Here Industry watchers see this as being an even bigger
Here Here
technological disruption – and greater market
Here
opportunity – than the emergence of the PC”
Here Here Here
– The Economist Technology Quarterly March 24th, 2001
Here
Here
43
44
Act: Tower …
Task for you to do!
Build a self supporting
structure 1.8 m tall
Use only A4 paper
and staples
45
46
Review structures. Discuss V & H … V
Vertical Integration
Traditional Telecom / H.323
Applications
Operating System
Processor Storage Memory
Physical Hardware
47
Horizontal Integration
Client / Server – Good IP Protocol like SIP
Apps Apps Apps
Operating Operating Operating
System System System
Micro-
Memory Processor Storage
Physical Physical Physical
Hardware Hardware Hardware
48
“When a horizontal
business model meets a
vertical business model…
…horizontal wins every
time.”
?
John Chambers, CISCO Systems CEO
49
Something to think about …
Think of a successful Internet
protocol.
What characteristics have made it
so successful?
50
Task:
Think of a successful
Internet protocol.
What characteristics
have made it so
successful?
Break
51
Characteristics of a Successful
Protocol
Characteristic Description
Simple Small number of components. Text based
Flexible Can meet evolving needs
Scalable Can work equally well at all levels
Extensible Can integrate with other protocols
Modular Building block approach
52
3 main VoIP Protocols
• H.323 Vertically Integrated
Vertical Integration
Traditional Telecom / H.323
• SIP Horizontally Integrated
Applications
Operating System
Processor Storage Memory
Physical Hardware
52
53
3 main VoIP Protocols
• H.323 Vertically Integrated
• SIP Horizontally Integrated
• MGCP & MEGACO
Softswitch
SS7
IP
Analogue
PSTN Phone
SIP
Phone
Gateway
54
55
End of intro … SIP detail
SIP
Session Initiation Protocol
56
What is SIP?
57
58
… SIP defines 3
SIP defines …
A range of SIP network components
A structure for communication and
exchange of information
A range of services
59
60
Doesn’t do …Need for software
this design that design
this code that code
Java C++
this interoperability that
SIP product products talk using SIP messages SIP product
61
By
Henning Schulzrinne
and
Jonathan Rosenberg
62
History… Quote
“At that stage, IP
telephony as a term
probably didn’t exist.
Initially SIP was intended
to create a mechanism for
inviting people to large
scale, multipoint
conferences.”
63
“After a short while it
became clear that,
technology wise, it was not
a significant jump from
where we were to setting up
point-to-point conferences
– essentially phone calls.
Once IP telephony became
the thing to do, people
started looking primarily at
using the protocol for voice
applications.”
64
“But the emphasis of SIP
has always been to remain
as independent as possible
of the media it underlies.”
Henning Schulzrinne
65
66
Key point – SIP does one thing… Other protocols
Sip works with other Protocols
Define media to
communication
media through
Transport the
decode voice
Encode and
be used in
Announce
multicast
sessions
session
session
session
Sets up
SIP SDP RTP SAP Codecs
Session Session Real Time Session encoding and
Initiation Description Protocol Announcement decoding
Protocol Protocol Protocol
67
68
How sip works. Is simple. Little defined… UAs
User agents
• Distributed intelligence in end-points
• Basic services conducted
independently from network
• Peer-to-peer communications using
client-server model
69
User Agent – both Client and Server
Client
Server
User Agent
70
User Agent – both Client and Server
Client
Server
User Agent
IP Network
Client
Server
User Agent
71
Simplest SIP Session – UA to UA
Invitation
Session Open
Invitation Accepted
72
73
Q: How message addressed? Demo Peer to Peer UA
UA to UA through IP Address
192.168.1.15
192.168.1.10
IP Network
192.168.1.14
192.168.1.11
192.168.1.13
192.168.1.12
192.168.1.12 calls 192.168.1.10
74
+44 (0) 1633 76600
192.168.1.24 ???
75
E-mail Address
dsheppard@ ubiquity.net
76
E-mail Address
dsheppard@ ubiquity.net
77
SIP Address
sip:dsheppard@ ubiquity.net
78
Registering with a SIP Registry Server
Proxy Server
Registry
79
Registering with a SIP Registry Server
Proxy Server
Registration
Current IP SIP URL
address
sip:dsheppard@ubiquity.net Registry
currently at 192.168.1.156
“Aha! Now I know that for this
session sip:dsheppard@ubiquity.net
is at 192.168.1.156”
80
After Registering with a Server
sip:bill@ubiquity.net
sip:david@ubiquity.net currently at 192.168.1.14
currently at 192.168.1.10
Proxy
Server sip:jane@ubiquity.net
currently at 192.168.1.13
sip:john@ubiquity.net
Registry
currently at 192.168.1.11
I know that …
sip:david@ubiquity.net is at 192.169.1.10
sip:john@ubiquity.net is at 192.169.1.11
sip:sue@ubiquity.net sip:sue@ubiquity.net is at 192.169.1.12
sip:jane@ubiquity.net is at 192.169.1.13
currently at 192.168.1.12
sip:bill@ubiquity.net is at 192.169.1.14
81
82
Q: Inherent benefit?
Inherent Benefit in SIP Registration
John usually
works here
Proxy
Server
User
Incoming call:
Mobility
Sue is calling
John on
sip:john@ubiquity.net
Today he is on
business in Africa
sip:john@ubiquity.net
currently at 171.163.1.36
83
Multiple Registrations
Simultaneous Forking sip:john@ubiquity.net
Proxy
Incoming call for sip:john@ ubiquity.net Server
Registry
Office
Lab
84
Multiple Registrations
Sequential Forking sip:john@ubiquity.net
Proxy
Incoming call for sip:john@ ubiquity.net Server
Registry
Office
Lab
85
One Number Reachability
User-centric, not device-centric
john@ubiquity.net
sip:john@ubiquity.net
86
Many to many
SIP URL / device relationship
In his spare time John
is also Coco the Clown,
a children’s entertainer sip:coco@entertainment.com
sip:john@ubiquity.net
Proxy
Incoming call for sip:coco@entertainment.com Server
Registry Office
Home
87
Many to many
SIP URL / device relationship
John also has a son, Charles
sip:charles@aol.com
sip:coco@entertainment.com
sip:john@ubiquity.net
Charles’
mobile
Proxy
Incoming call for sip:charles@aol.com Server
Registry Office
A SIP server can relate many URLs
Home
to many combinations of devices
88
89
Scale of network, 2 or more servers. Locating by address, 3 steps?
SIP Proxy Servers
I want to call
sip:sue@elsewhere.com
sip:david@ubiquity.net
currently at 192.168.1.156
How does the Proxy
Proxy Server know where to direct the
message?
Registry
Let’s find out …
ubiquity.net server
90
Proxy Servers: process of locating by a SIP address
elsewhere.com?
1. Check Local Domains table Table of Proxy
Support
Sarah… @192.168.1.112
Jim… @192.132.21.44
Dave… @192.99.3.121
Yes? Check for the User Name in Domains
Huy e… @ 192.124.221.133
Marketing
support.net Jane… @192.168.1.112
related Domain registrations marketing.net Steve… @192.132.21.44
Yes? Resolve the SIP URL to the IP development.net
Fr… @192.99.3.121
Development
Dranne… @ 192.124.221.133
sales.net Bill… @192.168.1.112
address bound to the user and forward SQA.net
training.net
Steve… @192.132.21.44
Dave… @192.99.3.121
Lianne… @ 192.124.221.133
to destination User Agent
elsewhere.com? admin.net
graphics.net
No? Go to Next Hop Server table check Table of Next- Hop Servers
ubiquity.co.uk… @193.168.15.134
columbia.edu … @194.146.14.22
2. Check Next Hop Servers table aol.com …
msm.com …
bt.co.uk …
@192.168.154.32
@145.158.18.37
@125.166.1.12
dt.de … @142.164.31.212
Yes? Resolve to bound Domain IP mdo.org …
ntl.co.uk …
Proxy Server
@148.134.41.121
@192.158.2.112
address and forward to that particular
Domain Proxy elsewhere.com?
Server DNS
No? Do DNS lookup
3. Do DNS lookup
Yes? Resolve to returned Domain Registry
IP address and forward to Domain
Proxy Server
No? Return ‘not found’ message to Sender
91
sip:sue@elsewhere.com?
SIP Proxy Servers
Table of Proxy
Domains
support.net
Table of Next-
marketing.net
Hop Servers
development.net
sales.net
ubiquity.co.uk
SQA.net
columbia.edu
training.net
aol.com
admin.net
msm.com
graphics.net
bt.co.uk
dt.de
mdo.org
Proxy Server ntl.co.uk
DNS
sip:david@ubiquity.net
currently at 192.168.1.156
Registry
elsewhere.com server
IP Network
to the plot.
… backelsewhere.com?
Table of Proxy
Domains
Proxy Server support.net
Table of Next-
marketing.net
Hop Servers
development.net
sales.net
ubiquity.co.uk
SQA.net
columbia.edu
training.net
aol.com
admin.net
msm.com
graphics.net
bt.co.uk
dt.de
mdo.org
Registry ntl.co.uk
DNS
sip:sue@elsewhere.com
ubiquity.net server currently at 193.167.1.121
92
SIP Proxy Servers
sip:david@ubiquity.net
currently at 192.168.1.156
IP Network
sip:sue@elsewhere.com
currently at 193.167.1.121
93
Multiple SIP Network Servers
… but signalling usually passes through just 2 or 3
94
95
Demo Reg & UA to UA call set up through server. Logical v. physical entities …Redirect S
SIP Redirect Server
Table of Proxy
Domains
support.netTable of Next-
marketing.net Servers
Hop
david@ubiquity.net?
development.net
sales.net ubiquity.co.uk
SQA.net columbia.edu
training.net
aol.com
admin.net msm.com
graphics.net
bt.co.uk
another-domain.com dt.de
mdo.org
ntl.co.uk
DNS
ubiquity.net
sip:david@another-domain.com
sip:david@ubiquity.net
Table of Proxy
Domains
support.netTable of Next-
marketing.net Servers
Hop
Ubiquity.net?
development.net
John’s default
sales.net ubiquity.co.uk
SQA.net columbia.edu
training.net
aol.com
admin.net msm.com
graphics.net
bt.co.uk
Proxy Server: dt.de
mdo.org
ntl.co.uk
DNS
@work.co.uk
sip:john@work.co.uk
wants to call sip:david@ubiquity.net
96
SIP Redirect Server
another-domain.com
sip:david@ubiquity.net
ubiquity.net
sip:david@another-domain.com
John’s default
Proxy Server :
@work.co.uk
sip:john@business.com
calling sip:david@ubiquity.net
97
SIP Redirect Server
another-domain.com
sip:david@ubiquity.net
ubiquity.net
Two Registrations:
98
SIP Redirect Server
another-domain.com
sip:david@ubiquity.net
ubiquity.net
Two Registrations:
1. Ubiquity server: Contact sip:david@ubiquity at
another-domain.com
99
SIP Redirect Server
another-domain.com
sip:david@ubiquity.net
ubiquity.net
Two Registrations:
2. Another-domain server: Contact sip:david@another-
domain.com at current IP address
Note: the current IP address is likely to be a private
address
100
101
Quick Quiz
Summary of SIP Components
• User Agent – UAC and UAS
• SIP Addresses and Registration
• Registrar Servers Althoughinlogically separate
entities, practice
• Proxy Servers developers are likely to
combine functions in a single
• Redirect Servers physical device
102
Summary of SIP Services
• User mobility – any location, any SIP enabled
device
• Single number reach-ability
• Forking – simultaneous or sequential
• Many to many SIP URL/device relationship
• Supports all types of media: audio, video, data,
text, etc
• Call ID and call history
• Click to dial from database or web page
• Web page push and pull (Manual )
• Multiparty, conference call (Manual set up)
103
Plenary
• Life before SIP – a context for
development
• Essential SIP Components
• Basic Services through SIP
• Questions
104
After Lunch …
• Advanced Services
• The SIP Network
• Signalling and Message
Flow
• SIP Methods
• Ubiquity and the Helmsman
Product Range
105
Lunch
106
Agenda - Afternoon
• Session 3
– Advanced Services
– The SIP Network
– Signalling and Message Flow
– SIP Methods
• Coffee Break
• Session 4
– Ubiquity and the Helmsman Product Range
– Plenary - Questions and Answers
107
Summary of SIP Components
• User Agent – UAC and UAS
• SIP Addresses and Registration
• Registrar Servers Althoughinlogically separate
entities, practice
• Proxy Servers developers are likely to
combine functions in a single
• Redirect Servers physical device
108
Summary of SIP Services
• User mobility – any location, any SIP enabled
device
• Single number reach-ability
• Forking – simultaneous or sequential
• Many to many SIP URL/device relationship
• Supports all types of media: audio, video, data,
text, etc
• Call ID and call history
• Click to dial from database or web page
• Web page push and pull (Manual )
• Multiparty, conference call (Manual set up)
109
innovation
110
More to SIP than Protocol …inno
If I give this some thought, I
can add to my UA code and
make it intelligently manipulate
and act upon SIP messages
for my benefit!
OPTION:
Link the UA to my
personal scheduler
and automatically
this design divert all my calls
to voice mail when
I’m in a meeting. SIP enabled
PDA device
this code
Java
Advanced
this
SIP product services
111
If I give this some thought, I can
add to my server code and
make it intelligently manipulate
and act upon SIP messages for
the benefit of my customers!
Include server code that design
that will allow user
groups to know the that code
current status of group C++
members: on/off line, Advanced
that
available/on another services SIP product
call, etc. Presence!
112
Interoperability V. Proprietary?
this design
that design
this code that code
Java C++
this Interoperability that
SIP product SIP product
Products talk using SIP messages
Advanced Advanced
services Interoperability??? services
113
114
Analogy …cookery book
+ recipe =
115
+ innovation =
116
117
…ASB
Server
keeps state
…is Stateful
Database
Application Service Broker
118
Examples…
119
Presence
Guillaume
???
Adam
Michael
Raman
Mathew
Helmsman SIP
Proxy Server +
Application Services
Broker. Dave
120
Instant Message
currently unavailable
Unavailable
Guillaume
message:
I need to
speak with
you urgently
Helmsman SIP
Proxy Server +
Application Services
Broker. Dave
121
Conference call
Raman
Obtain presence
for conference call
Guillaume
Adam Dave
Send instant message to conference
Set up conference
Add additional party
Michael
Mathew
122
Web call centres
Distributed Call Centre
Call centre assistants can
be located anywhere`
The server database
contains information
about the skills of each
assistant.
The server manages the
information displayed to
the user and the assistant.
123
124
Write scripts
Web call centres
Distributed Call
Centre
Intelligent Call
Centre Routing
Sylvia
I want to ask
about booking
this concert
ticket
125
126
Web call centres
Distributed Call
Centre
Intelligent Call
Centre Routing
Je voudrais
acheter un
livre de John
Saul.
Emmanuel
Les
Livres
Les livres?
John Saul?
127
128
Web call centres
Distributed Call
Centre
Intelligent Call
Centre Routing
And Profiling
Sylvia
Caller profile
pops on screen
I want to check
my flight details
Bernadette
129
130
Unsolicited SIP
Intelligent Call Waiting
salesman Phone
Automatically
rejected
Unknown caller …
… Ravinder is busy.
Ravinder Zoe
131
Intelligent Call Waiting
Analogue
…call from Grandma! Phone
IAD device
Grandma
Instant popup message:
Grandma is
calling
Ravinder Zoe
132
133
Booking a Hotel
…push web page!
Wayne
134
Delivery service
Frank’s wife
Frank’s wife
Makes order through web
page and/or click to dial
Frank
135
Delivery service
Frank’s wife
Frank
Notification of arrival
136
Financial Sector
• Call bank and automatically receive statement
• Account transaction triggers call of notification
• Presence triggers stock status update
• Presence triggers personalised advertisement to
be sent
• User looking at statement on the Internet clicks
to dial bank
137
Summary of Innovative SIP Services
• Presence & related automated functions
• Instant messaging
• Automated conference call – 3rd party call control
• Advanced personalised call manipulation – call again at…
• Distributed call centres & intelligent call routing
• Intelligent call waiting
• Automated web page / profile pull / push
• Automatically triggered actions – event notification
• IP Centrex – local or remote
• Profile management
… and more …
138
Time for a short break
139
AS are tailored to SPs spec/requirements. Proprietary. Hook for customers.
Agenda - Afternoon
• Session 3
– The SIP Network
– Signalling and Message Flow
– SIP Methods
• Coffee Break
• Session 4
– Ubiquity and the Helmsman Product Range
– Plenary - Questions and Answers
140
141
SIP Networks
A SIP network architecture
Locator
Server
Registrar DHCP
Server User
Profile
DNS
Server
Database
IP
Firewall SIP
Phone
Firewall
SIP
Phone SIP Server
SS7
Gateway
IP
SIP -Enabled
SIP Server
Router
Analogue
Phone PSTN
SIP Server Analogue
Phone
Gateway
SIP Soft
User Agent
IP
H.323
142
Connection to the PSTN
PSTN linked via a gateway to the IP services
SS7
PSTN
Gateway
Analogue
Phone
143
Connection to the PSTN
PSTN linked via a gateway to the IP services
PSTN
Gateway
Analogue
Phone
SIP
PSTN
Gateway
Analogue
Phone
144
Connection to Today’s Mobile
SS7
PSTN
Gateway
145
Connection to Tomorrow’s 3G
3GPP will be a complete IP system
3GPP will use SIP for signalling
146
147
SIP is simple. (Remind Act). … 12msg
SIP Messages – just 12 of them!
Requests x 6 Client
1. REGISTER
2. INVITE Server
3. ACK
4. BYE User Agent
5. OPTIONS
6. CANCEL Responses x 6
1. 1xx Provisional
Client 2. 2xx Success
Server
3. 3xx Redirection
4. 4xx Request Failure
5. 5xx Server Failure
User Agent 6. 6xx Global Failure
148
SIP Requests
REGISTER to register with the server
INVITE to invite someone to join a session
ACK to acknowledge confirmation of session
parameter exchange
BYE to terminate a session
OPTIONS to seek information about a session
member
CANCEL to cancel a pending request
149
SIP Responses
Client
Server
Client User Agent
Server
From UA Server to UA Client
User Agent
150
SIP Responses
1xx Provisional reports progress to the caller
2xx Success call accepted
3xx Redirection callee not at address. Try again at …
4xx Request Failure request failed because …
5xx Server Failure
6xx Global Failure
151
152
Simple. .. Call flow UA 2 UA
Call Flow – UA to UA
INVITE
Includes
Caller description of
Callee
INVITE sip:bill@work.com SIP/2.0
Caller’s available
media options
To: Bill<sip:bill@work.com>
From: John<sip:john@home.com>
Call-ID: 267343@192.168.1.212
Time
Via: SIP/2.0/UDP 192.168.1.212
Contact: john@142.136.14.223
CSeq: 1 INVITE
Content-Type: application/SDP
Content-Length: 124
CRLF
v=0
o=192.168.1.212 IN IP4 192.168.1.212
s= Call from John
c=IN IP4 192.168.1.212
m=audio 5004 RTP/AVP 8 3 0
153
Call Flow – UA to UA
Caller Callee
100 Trying
180 Ringing
200 OK
Time
ACK Includes
description of
Callee’s available
media options
Session Open
BYE
200 OK
154
Call Flow – UA to UA
Caller Callee
Time
Session Terminated
155
Call Flow – UA to UA
INVITE
Caller 100 Trying Callee
180 Ringing
200 OK
Time
ACK
Session Open
BYE
200 OK
Session terminated
156
Registering a UA with a Server
Proxy
Server
User Registry
REGISTER
200 OK
Time
User Registered
157
Registering a UA with a Server
Proxy
Server
User Registry
REGISTER
200 OK
Time
User Registered
158
Call Flow – UA to UA via Proxy
INVITE
UA 100 Trying Proxy UA
Includes
description of INVITE
Caller’s available
media options 100 Trying
Includes
description of 180 Ringing
Caller’s available
180 Ringing media options
Time
200 OK
200 OK
Includes
ACK description of
Includes Callee’s available
description of media options
Callee’s available
Session Open
media options
BYE
200 OK
159
Call Flow – UA to UA via Proxy
UA Proxy UA
Time
Session terminated
160
Call Flow – UA to UA via Proxy
INVITE
UA 100 Trying Proxy UA
INVITE
100 Trying
180 Ringing
180 Ringing
Time
200 OK
200 OK
ACK
Session Open
BYE
200 OK
Session terminated
161
162
Invite Qs… BBall
Basket Ball ???
163
164
Review flow … Message content
SIP Messages
• Functions of a SIP Message
• Constructing an INVITE Request
• Constructing a 200 OK Response
165
SIP Messages – 4 Functions
Define the purpose of the message
Declare who is involved with the
message
Enable delivery of ‘Non-SIP’ media
Ensure that servers always process the
message in relation to other messages
in a SIP session, in the correct sequence
166
SIP Requests – from Client to Server
Client
Server
User Agent or Server
Client
Server
User Agent
167
An INVITE Request
INVITE sip:bill@work.com SIP/2.0
To: Bill<sip:bill@work.com>
From: John<sip:john@home.com>
Call-ID: 267343@192.168.1.212
Via: SIP/2.0/UDP 192.168.1.212
Contact: john@192.168.1.212
CSeq: 1 INVITE
Content-Type: application/SDP
Content-Length: 124
CRLF
v=0
o=192.168.1.212 IN IP4 192.168.1.212
s= Call from John
c=IN IP4 192.168.1.212
m=audio 5004 RTP/AVP 8 3 0
168
Constructing an INVITE Request
INVITE sip:bill@work.com SIP/2.0
Defines purpose of
message
169
Constructing an INVITE Request
INVITE sip:bill@work.com SIP/2.0
Defines purpose of
To: Bill<sip:bill@work.com>
From: John<sip:john@home.com>
message
Declares who the
Contact: john@192.168.1.212 message relates to
170
Constructing an INVITE Request
INVITE sip:bill@work.com SIP/2.0
Defines purpose of
To: Bill<sip:bill@work.com>
From: John<sip:john@home.com>
message
Declares who the
Contact: john@192.168.1.212 message relates to
Content-Type: application/SDP Enables delivery of
Content-Length: 124 non-SIP media
CRLF
v=0
Message Body content is
o=192.168.1.212 IN IP4 192.168.1.212
s= Call from John c=IN IP4
insignificant to SIP
192.168.1.212
m=audio 5004 RTP/AVP 8 3 0
.
171
Constructing an INVITE Request
INVITE sip:bill@work.com SIP/2.0
Defines purpose of
To: Bill<sip:bill@work.com>
From: John<sip:john@home.com>
message
Call-ID: 267343@192.168.1.212
Declares who the
Contact: john@192.168.1.212 message relates to
CSeq: 1 INVITE
Content-Type: application/SDP Enables delivery of
Content-Length: 124 non-SIP media
Ensures request
v=0
o=192.168.1.212 IN IP4 192.168.1.212
can be related to
s= Call from John other messages in
c=IN IP4 192.168.1.212 session
m=audio 5004 RTP/AVP 8 3 0
172
Constructing an INVITE Request
INVITE sip:bill@work.com SIP/2.0
Defines purpose of
To: Bill<sip:bill@work.com>
From: John<sip:john@home.com>
message
Call-ID: 267343@192.168.1.212
Via: SIP/2.0/UDP 192.168.1.212
Declares who the
Contact: john@192.168.1.212 message relates to
CSeq: 1 INVITE
Content-Type: application/SDP Enables delivery of
Content-Length: 124 non-SIP media
Ensures request
v=0
o=192.168.1.212 IN IP4 192.168.1.212
can be related to
s= Call from John other messages in
c=IN IP4 192.168.1.212 session
m=audio 5004 RTP/AVP 8 3 0
Records path
173
Elements of an INVITE Request
INVITE sip:bill@work.com SIP/2.0
Start Line
To: Bill<sip:bill@work.com>
From: John<sip:john@home.com>
Call-ID: 267343@192.168.1.212
Via: SIP/2.0/UDP 192.168.1.212 Headers
Contact: john@192.168.1.212
CSeq: 1 INVITE
Content-Type: application/SDP
Content-Length: 124
CRLF
v=0
o=192.168.1.212 IN IP4 192.168.1.212
s= Call from John Message
c=IN IP4 192.168.1.212
m=audio 5004 RTP/AVP 8 3 0
Body
174
SIP Responses – from Server to Server
Client
Server
User Agent or Server
Client
Server
User Agent
175
A 100 Trying Response
SIP/2.0 100 Trying
To: Bill<sip:bill@work.com>
From: John<sip:john@home.com>
Call-ID: 267343@192.168.1.212
Via: SIP/2.0/UDP 192.168.1.212
CSeq: 1 INVITE
Content-Length: 0
176
Much of the header information is the same
INVITE sip:bill@work.com SIP/2.0 SIP/2.0 100 Trying
To: Bill<sip:bill@work.com> To: Bill<sip:bill@work.com>
From: John<sip:john@home.com> From: John<sip:john@home.com>
Call-ID: 267343@192.168.1.212 Call-ID: 267343@192.168.1.212
Via: SIP/2.0/UDP 192.168.1.212 Via: SIP/2.0/UDP 192.168.1.212
Contact: john@192.168.1.212 CSeq: 1 INVITE
CSeq: 1 INVITE Content-Length: 0
Content-Type: application/SDP
Content-Length: 124
v=0
o=192.168.1.212 IN IP4 192.168.1.212
s= Call from John
c=IN IP4 192.168.1.212
m=audio 5004 RTP/AVP 8 3 0
177
A 100 Trying Response
SIP/2.0 100 Trying
Defines purpose of
message
178
A 100 Trying Response
SIP/2.0 100 Trying
Defines purpose of
To: Bill<sip:bill@work.com>
message From: John<sip:john@home.com>
Declares who the
message relates to
179
A 100 Trying Response
SIP/2.0 100 Trying
Defines purpose of
To: Bill<sip:bill@work.com>
message From: John<sip:john@home.com>
Declares who the
message relates to
Content-Length: 0
No message body
in 100 Trying
.
180
A 100 Trying Response
SIP/2.0 100 Trying
Defines purpose of
To: Bill<sip:bill@work.com>
message From: John<sip:john@home.com>
Call-ID: 267343@192.168.1.212
Declares who the
message relates to CSeq: 1 INVITE
Content-Length: 0
Ensures request
can be related to
other messages in
session
181
A 100 Trying Response
SIP/2.0 100 Trying
Defines purpose of
To: Bill<sip:bill@work.com>
message From: John<sip:john@home.com>
Call-ID: 267343@192.168.1.212
Declares who the Via: SIP/2.0/UDP 192.168.1.212
message relates to CSeq: 1 INVITE
Content-Length: 0
Ensures request
can be related to
other messages in
session
Uses Recorded path
182
A 200 OK Response to INVITE
SIP/2.0 200 OK
To: Bill<sip:bill@work.com>
From: John<sip:john@home.com>
Call-ID: 267343@192.168.1.212
Via: SIP/2.0/UDP 192.168.1.212
Contact: bill@192.126.1.103
CSeq: 1 INVITE
Content-Type: application/SDP
Content-Length: 121
CRLF
v=0
o=192.126.1.103 IN IP4 192.126.1.103
s=Call from John
c=IN IP4 192.168.1.212
m=audio 5004 RTP/AVP 3 0
183
Much of the header information is the same
INVITE sip:bill@work.com SIP/2.0 SIP/2.0 200 OK
To: Bill<sip:bill@work.com> To: Bill<sip:bill@work.com>
From: John<sip:john@home.com> From: John<sip:john@home.com>
Call-ID: 267343@192.168.1.212 Call-ID: 267343@192.168.1.212
Via: SIP/2.0/UDP 192.168.1.212 Via: SIP/2.0/UDP 192.168.1.212
Contact: john@192.168.1.212 Contact: bill@192.126.1.103
CSeq: 1 INVITE CSeq: 1 INVITE
Content-Type: application/SDP Content-Type: application/SDP
Content-Length: 124 Content-Length: 121
v=0 v=0
o=192.168.1.212 IN IP4 192.168.1.212 o= 192.126.1.103 IN IP4 192.126.1.103
s= Call from John s=Response from Bill
c=IN IP4 192.168.1.212 c=IN IP4 192.126.15.103
m=audio 5004 RTP/AVP 8 3 0 m=audio 5004 RTP/AVP 3 0
184
A 200 OK Response to INVITE
SIP/2.0 200 OK
Defines purpose of
message
185
A 200 OK Response to INVITE
SIP/2.0 200 OK
Defines purpose of
To: Bill<sip:bill@work.com>
message From: John<sip:john@home.com>
Declares who the
message relates to Contact: bill@192.126.1.103
186
A 200 OK Response to INVITE
SIP/2.0 200 OK
Defines purpose of
To: Bill<sip:bill@work.com>
message From: John<sip:john@home.com>
Declares who the
message relates to Contact: bill@192.126.1.103
Enables delivery of Content-Type: application/SDP
non-SIP media Content-Length: 121
CRLF
v=0
o= 192.126.1.103 IN IP4 192.126.1.103
s= Response from Bill
c=IN IP4 192.126.15.103
m=audio 5004 RTP/AVP 3 0
.
187
A 200 OK Response to INVITE
SIP/2.0 200 OK
Defines purpose of
To: Bill<sip:bill@work.com>
message From: John<sip:john@home.com>
Call-ID: 267343@192.168.1.212
Declares who the
message relates to Contact: bill@192.126.1.103
CSeq: 1 INVITE
Enables delivery of Content-Type: application/SDP
non-SIP media Content-Length: 121
Ensures request
v=0
can be related to o= 192.126.1.103 IN IP4 192.126.1.103
other messages in s= Response from Bill
session c=IN IP4 192.126.1.103 m=audio 5004
RTP/AVP 3 0
188
A 200 OK Response to INVITE
SIP/2.0 200 OK
Defines purpose of
To: Bill<sip:bill@work.com>
message From: John<sip:john@home.com>
Call-ID: 267343@192.168.1.212
Declares who the Via: SIP/2.0/UDP 192.168.1.212
message relates to Contact: bill@192.126.1.103
CSeq: 1 INVITE
Enables delivery of Content-Type: application/SDP
non-SIP media Content-Length: 121
Ensures request
v=0
can be related to o= 192.126.1.103 IN IP4 192.126.1.103
other messages in s= Response from Bill
session c=IN IP4 192.126.15.103
m=audio 5004 RTP/AVP 3 0
Uses Recorded path
189
190
Act: Generate Request
After the break …
• Session 4
– Ubiquity and the Helmsman
Product Range
– Plenary - Questions and
Answers
191
Coffee Break
192
