SIP - More than meets the eye Speakers: Ofer Cohen - VOIP Group Leader, LivePerson Yossi Maimon - VOIP Technical Leader, LivePerson An Introduction to the SIP protocol. SIP Position in telecommunication networks and the content services. What is SIP: The Session Initiation Protocol (SIP) is a signaling communications protocol, widely used for controlling multimedia communication sessions such as voice and video calls over Internet Protocol (IP) networks. The protocol defines the messages that are sent between peers which govern establishment, termination and other essential elements of a call. SIP can be used for creating, modifying and terminating sessions consisting of one or several media streams. SIP can be used for two-party (unicast) or multiparty (multicast) sessions. Other SIP applications include video conferencing, streaming multimedia distribution, instant messaging, presence information, file transfer, fax over IP and online games. (Source: Wikipedia)

1. SIP – Session Initiation Protocol
March, 2014
LP Voice Team
More than meets the

2. 1
Yossi Maimon - LivePerson VOIP Technical Leader
Ofer Cohen - LivePerson VOIP Group Leader
More than 15 years of experience in telecom networks.
Especially with conversions systems.
About the Presenters
FMC, IMS, IFC, IPT, CTI, GW, IN, VSSF, SIPT, MSC GW, SIP Tunneling over Https, Media Transcoding, SIM-IP Softphone

3. 1Chapter headings
Part 1 1. Telecom in a Nutshell
2. How IP became a common mediator network
3. One word on IMS
Part 2 4. SIP Base flow
Part 3 5. SIP Content services.
Part 4 6. IMS

4. 1Chapter headings
Part 1 1. Telecom in a Nutshell
2. How IP became a common mediator network
3. One word on IMS
Part 2 4. SIP Base flow
Part 3 5. SIP Content services.
Part 4 6. IMS

5. 1The IP effect in telecom networks
IP

6. 1Telecom in a Nutshell
• Analog Networks (PSTN)
• Digital networks
• Mobile
• Phone over IP

7. 1Telecom in a Nutshell
• Analog Networks (PSTN)
Analog, CS,
PSTN as ―telephony Internet‖,
Evolution.
• Digital networks
• Mobile
• Phone over IP

8. 1Telecom in a Nutshell
• Analog Networks (PSTN)
• Digital networks
ISDN – Integrated Services Digital Network.
IN services.
GW to PSTN.
• Mobile
• Phone over IP

9. 1Telecom in a Nutshell
• Analog Networks (PSTN)
• Digital networks
ISDN – Integrated Services Digital Network.
IN services.
GW to PSTN.
• Mobile
• Phone over IP

10. 1Telecom in a Nutshell
• Analog Networks (PSTN)
• Digital networks
ISDN – Integrated Services Digital Network.
IN services.
GW to PSTN.
• Mobile
• Phone over IP

11. 1Telecom in a Nutshell
• Analog Networks (PSTN)
• Digital networks
ISDN – Integrated Services Digital Network.
IN services.
GW to PSTN.
• Mobile
• Phone over IP

12. 1Telecom in a Nutshell
• Analog Networks (PSTN)
• Digital networks
ISDN – Integrated Services Digital Network.
IN services.
GW to PSTN.
• Mobile
• Phone over IP

13. 1Telecom in a Nutshell
• Analog Networks (PSTN)
• Digital networks
ISDN – Integrated Services Digital Network.
IN services.
GW to PSTN.
• Mobile
• Phone over IP

14. 1Telecom in a Nutshell
• Analog Networks (PSTN)
• Digital networks
ISDN – Integrated Services Digital Network.
IN services.
GW to PSTN.
• Mobile
• Phone over IP

15. 1Telecom in a Nutshell
• Analog Networks (PSTN)
• Digital networks
ISDN – Integrated Services Digital Network.
IN services.
GW to PSTN.
• Mobile
• Phone over IP

16. 1Telecom in a Nutshell
• Analog Networks (PSTN)
• Digital networks
ISDN – Integrated Services Digital Network.
IN services.
GW to PSTN.
• Mobile
• Phone over IP

17. 1Telecom in a Nutshell
• Analog Networks (PSTN)
• Digital networks
ISDN – Integrated Services Digital Network.
IN services.
GW to PSTN.
• Mobile
• Phone over IP
Analog
Network

18. 1Telecom in a Nutshell
• Analog Networks (PSTN)
• Digital networks
• Mobile
Just the endpoint is ―mobile‖.
Analog, GSM, 3G
Integrated into SS7, use ISDN as GW.
4G
• Phone over IP
Digital
Analog
IP

19. 1Telecom in a Nutshell
• Analog Networks (PSTN)
• Digital networks
• Mobile
Just the endpoint is ―mobile‖.
Analog, GSM, 3G
Integrated into SS7, use ISDN as GW.
4G
• Phone over IP
Digital
Analog
IP

20. 1Telecom in a Nutshell
• Analog Networks (PSTN)
• Digital networks
• Mobile
• Phone over IP
LAN
LAN
IP

21. 1Telecom in a Nutshell
• Analog Networks (PSTN)
• Digital networks
• Mobile
• Phone over IP
H.323, Skinny, H.324m, Skype, SIP
LAN
LAN
IP

22. 1
IP as a mediator
LAN
LAN
IP
Telecom in a Nutshell

23. 1
IP as a mediator
LAN
LAN
IP
Telecom in a Nutshell

24. 1
IP as a mediator
LAN
LAN
IP
Telecom in a Nutshell

25. 1Chapter headings:
Part 1 1. Telecom in a Nutshell
2. How IP became a common mediator network
3. One word on IMS
Part 2 4. SIP Base flow
Part 3 5. SIP Content services.
Part 4 6. IMS

26. 1How IP became a mediator network
ISDN

27. 1
ISDN
ISDN
How IP became a mediator network
ISDN
IP

28. 1
ISDN
ISDN
How IP became a mediator network
ISDN
ISDN
IP

29. 1
ISDN
ISDN
How IP became a mediator network
ISDN
ISDN
IP
IP
IP

30. 1
ISDN
ISDN
How IP became a mediator network
ISDN
ISDN
IP
IP
IP

31. 1
ISDN
ISDN
How IP became a mediator network
ISDN
ISDN
LTE / IMS
IP
IP
IP

32. 1How IP became a common mediator network
• Simple Integration with IP networks, decrease
communication cost.
• Phone became a content device and not just
phone-call device.
• One integration
IP
Service
Digital
Digital
IP
IP

33. 1
• Simple / HTTP style.
• Ability to capsulate foreign protocols.
• The dominate architecture for internet integration
are using* SIP.
*
IMS: SIP based
FMC: Major functions
Soft Switch : Common implementations.
Why SIP and not other IP Protocols

34. 1Chapter headings:
Part 1 1. Telecom in a Nutshell
2. How IP became a common mediator network
3. One word on IMS
Part 2 4. SIP Base flow
Part 3 5. SIP Content services.
Part 4 6. IMS

35. 1One word on IMS
IMS - IP Multimedia Subsystem

36. 1One word on IMS
IMS
Services scheduler
CSCFHSS
ServiceServiceServiceService

37. 1One word on IMS
IMS
Re-router
CSCFHSS
OUT
ServiceServiceServiceService

38. 1One word on IMS
IMS
Adapt networks
according their
abilities.
CSCFHSS
SIP NON SIP
OUT
ServiceServiceServiceService

39. 1Chapter headings
Part 1 1. Telecom in a Nutshell
2. How IP became a common mediator network
3. One word on IMS
Part 2 4. SIP Base flow
Part 3 5. SIP Content services.
Part 4 6. IMS

40. 1SIP Protocol
Communication session = Signaling + Media
Signaling: initiating,
Capability exchange,
Media: The content itself – voice, video, message, files, control events, …
Signaling: modifying,
terminating a session.

41. 1SIP Protocol
The SIP Define IP Signaling Session.
The session may initiated by:
• IP endpoint (SIP Phone, Click-To-Call, etc.)
• GW/Soft-Switch/FMC (Legacy to IP).
• Invoked as a mid-service.
IP
Service
Digital
Digital
IP
IP

42. 1SIP Protocol
SIP message is HTTP like:
text base.
request response.
head line, headers, body.
Example of Network elements
• User Agent – UAC, UAS
• Proxy server
• Registrar
• Redirect server
Example of SIP Request:
• Invite
• Bye
• Cancel
• Register

43. 1SIP Protocol
SIP Response:
• 1xx—Provisional Responses
• 2xx—Successful Responses
• 3xx—Redirection Responses
• 4xx—Client Failure Responses
• 5xx—Server Failure Responses
• 6xx—Global Failure Responses
Example for responses for Invite request:
180 Ringing
200 OK
302 Moved Temporarily
404 Not Found
407 Proxy Authentication Required
503 Service Unavailable

44. 1SIP Protocol
The Body may contains any type.
SDP: Capability declaration - voice, video, data, application, control, (text,
message).
XML / TXT.
MULTI: Usually in order to cover foreign protocols.
INVITE sip:972747004557@1.2.3.4 SIP/2.0
Call-ID: dd7705b18faf7bc6ae1da6bb3903a5ec@1.2.3.4
CSeq: 1 INVITE
From: <sip:972543080675@1.2.3.4>;tag=4882894371614
To: <sip:972747004557@1.2.3.4>
Content-Type: application/sdp
Contact: <sip:600_0@1.2.3.4;transport=udp>
Via: SIP/2.0/UDP 1.2.3.4:5060;branch=z9hG4bK49ddba9a2ba8c7ec
Content-Length: 126
v=0
o=app-name 0 0 IN IP4 192.1.2.3
s=SIP-Call
c=IN IP4 192.1.2.3
m=audio 27174 RTP/AVP 0 18
a=rtpmap:0 PCMU/8000
a=rtpmap:18 g729a/8000
a=fmtp:18 annexb=yes

45. 1Native basic flow to basic flow
Register BOB
ALICE BOB
200 ok
Invite BOB
200 ok
ACK
BYE
200 ok
Registrar

46. 1SIP INVITE
INVITE sip:bob@lp.com SIP/2.0
Via: SIP/2.0/UDP alice.lp.com;branch=z9hG4bK776asdhds
To: Bob <sip:bob@lp.com>
From: Alice <sip:alice@lp.com>;tag=1928301774
Call-ID: a84b4c76e66710@pc33.atlanta.com
CSeq: 1 INVITE
Contact: <sip:alice@pc33.atlanta.com>
Content-Type: application/sdp
Content-Length: 142
v=0
o=Alice 2890844526 2890844526 IN IP4 host.atlanta.example.com
c=IN IP4 alice.example.com
m=message 7394 TLS/MSRP *
a=accept-types:text/plain
a=path:msrp://alice.example.com:7394/2s93i9ek2a;tcp

47. 1SIP INVITE – VIA &Contact headers
INVITE sip:bob@lp.com SIP/2.0
Via: SIP/2.0/UDP alice.lp.com;branch=z9hG4bK776asdhds
To: Bob <sip:bob@lp.com>
From: Alice <sip:alice@lp.com>;tag=1928301774
Call-ID: a84b4c76e66710@pc33.atlanta.com
CSeq: 1 INVITE
Contact: <sip:alice@pc33.atlanta.com>
Content-Type: application/sdp
Content-Length: 142
v=0
o=Alice 2890844526 2890844526 IN IP4 host.atlanta.example.com
c=IN IP4 alice.example.com
m=message 7394 TLS/MSRP *
a=accept-types:text/plain
a=path:msrp://alice.example.com:7394/2s93i9ek2a;tcp

48. 1SIP INVITE - BODY
INVITE sip:bob@lp.com SIP/2.0
Via: SIP/2.0/UDP alice.lp.com;branch=z9hG4bK776asdhds
To: Bob <sip:bob@lp.com>
From: Alice <sip:alice@lp.com>;tag=1928301774
Call-ID: a84b4c76e66710@pc33.atlanta.com
CSeq: 1 INVITE
Contact: <sip:alice@pc33.atlanta.com>
Content-Type: application/sdp
Content-Length: 142
v=0
o=Alice 2890844526 2890844526 IN IP4 host.atlanta.example.com
c=IN IP4 alice.example.com
m=message 7394 TLS/MSRP *
a=accept-types:text/plain
a=path:msrp://alice.example.com:7394/2s93i9ek2a;tcp

49. 1Alice Registers to LP1, BOB to LP2
Register
200 ok 200 ok
RegisterLP1.COM LP2.COM
ALICE BOB

50. 1Alice calls BOB and gets Music on Hold
ALICE BOB
LP2.COM
IVR
LP1.COM
redirect
server
Invite BOB + SDP Alice
200 ok + SDP IVR

51. 1redirect the call to LP2
LP2.COM
IVR
LP1.COM
redirect
server
ALICE BOB

52. 1LP1 routes the call to BOB via LP2
ALICE BOB
IVR
Invite BOB + Alice SDP
200 ok with BOB SDP
Invite BOB + LP2 SDP
200 ok LP2 SDP
LP2.COMLP1.COM
redirect
server

53. 1Connect the media between Alice and BOB through LP2
IVR
(re) Invite + LP2 SDP
200 ok
redirect
server
ALICE BOB
LP2.COMLP1.COM

54. 1Disconnect IVR
IVR
redirect
server
ALICE BOB
LP2.COMLP1.COM

55. 1
LP2.COM
IVR
LP1.COM
redirect
server
ALICE BOB
Connect the media between Alice and BOB through LP2

56. 1Chapter headings
Part 1 1. Telecom in a Nutshell
2. How IP became a common mediator network
3. One word on IMS
Part 2 4. SIP Base flow
Part 3 5. SIP Content services.
Part 4 6. IMS

57. 1SIP Content Services
SIP is used by:
• SIP Devices.
• Converters to SIP-Based network:
GW
Soft Switch
SIP-T, SIP-I : protocols that allow ISUP messages to be transported over SIP networks.
FMC (Fixed mobile convergence): collection of services and abilities. Used by SIP for redirection, forking,
seamless switches etc.
IMS (IP Multimedia Subsystem): architectural framework for delivering IP multimedia services. It define an
integration of other networks with Internet services.
• IP Content Services
IP
Service
DigitalIP
IP Digital

58. 1SIP Content Services
SIP is used by:
• SIP Devices.
• Converters to SIP-Based network:
GW
Soft Switch
SIP-T, SIP-I : protocols that allow ISUP messages to be transported over SIP networks.
FMC (Fixed mobile convergence): collection of services and abilities. Used by SIP for redirection, forking,
seamless switches etc.
IMS (IP Multimedia Subsystem): architectural framework for delivering IP multimedia services. It define an
integration of other networks with Internet services.
• IP Content Services
IP
Service
DigitalIP
IP Digital

59. 1SIP Content Services
• Unified communication.
• Device hunting (sequential dialing).
• Seamless network switch (VCC, MCM).
• Media manipulation
Text to speech, Recording, Lawful interception,
conference with side streaming (distance learning).
• Remote Camera control.
• Smartphone application wakeup.
• In-Browser application (WebRtc).
• Presence server (Sync IM presence and Calendar)
• Reflect PBX Phones (CTI to IMS).
• Pull call/chat to mobile.
• Location service (use Cell location for chat application)
• Mobile event (lost my phone, unmute lost phone,..)

60. 1Example
Alice and Bob Signaling Session

61. 1SIP abilities - Example
Alice Bob

62. 1SIP abilities - Example
Alice BobBob get update in its IM application about Alice location
location
IM applicationLocation application

63. 1
Alice
SIP abilities - Example
Bob
IM application
Bob get update in its IM application about Alice location
So he sends her a message.

64. 1
Alice
SIP abilities - Example
BobBob get update in its IM application about Alice location
So he sends her a message.
Alice call Bob through a UC system
UC Server

65. 1
Alice
SIP abilities - Example
BobBob get update in its IM application about Alice location
So he sends her a message.
Alice call Bob through a UC system
Bob cellular is off, other devices keep ringing.
UC Server

66. 1
Alice
SIP abilities - Example
BobBob get update in its IM application about Alice location
So he sends her a message.
Alice call Bob through a UC system
Bob cellular is off, other devices keep ringing.
Bob reject the call from one of his devices
UC Server

67. 1
Alice
SIP abilities - Example
BobBob get update in its IM application about Alice location
So he sends her a message.
Alice call Bob through a UC system
Bob cellular is off, other devices keep ringing.
Bob reject the call from one of his devices
System detect a ‗human reject‘ and cancel all devices.
UC Server
reject

68. 1SIP Content Services
• Unified communication.
• Device hunting (sequential dialing).
• Seamless network switch (VCC, MCM).
• Media manipulation
Text to speech, Recording, Lawful interception
conference with side streaming (distance learning).
• Remote Camera control.
• Smartphone application wakeup.
• In-Browser application (WebRtc).
• Presence server (Sync IM presence and Calendar)
• Reflect PBX Phones (CTI to IMS).
• Pull call/chat to mobile.
• Location service (use Cell location for chat application)
• Mobile event (lost my phone, unmute lost phone,..)

69. 1SIP Content Services
IP
Service
DigitalIP
IP Digital

70. Q & A

71. Thank you

72. 1
IMS - IP Multimedia Subsystem

73. Thank you