SIP Session Timer

1
SIP Session Timer

• Jonathan Rosenberg
• dynamicsoft

2
Changes

• Significant overhaul from previous version
• Motivation list discussion on supporting
  function when only one of UAS/UAC knows extension

• Works since you dont need to support it to
  receive re-invites
• Want either side to perform reinvites

3
Call Flow
INV ktimer S-T 500
INV ktimer

• UAC supports, UAS doesnt
• 200 OK wont have S-T
• Last proxy that inserted S-T inserts S-T value
  Require into response
• Requires stateful S-T proxies

200 OK Require timer S-T 500
200 OK
ACK
ACK
INV ktimer S-T 500
INV ktimer
UAC
UAS
Proxy
4
Call Flow
INV S-T 500
INV

• UAS supports, UAC doesnt
• No Supported in INVITE
• Proxy inserts S-T anyway
• UAS reflects S-T, no Require, knows it is doing
  re-INVITES

200 OK S-T 500
200 OK S-T 500
ACK
ACK
INV ktimer S-T 500
INV ktimer S-T 500
UAC
UAS
Proxy
5
Call Flow
INV S-T 500
INV

• Neither Supports
• Proxy inserts S-T timer even though no Supported
• No S-T in response
• Proxy doesnt insert S-T or Require

200 OK
200 OK
ACK
ACK
UAC
UAS
Proxy
6
Call Flow
INVktimer S-T 500
INVktimer

• Both Support
• Same as previous drafts
• UAC will perform timer
• Open issues
• reinvite issues?

200 OK S-T 500 Require timer
200 OK S-T 500 Require timer
ACK
ACK
INV ktimer S-T 500
INV ktimer
UAC
UAS
Proxy