Open Issues in SIP Service Examples Recent Changes

1
Open Issues in SIP Service ExamplesRecent
Changes

• Added SUBSCRIBE/NOTIFY using Dialog Event
  Package
• Added Single Line Extension Flow
• Added Auto Callback Flow
• Changed to Require replaces instead of
  Accept-Contact for Attended Transfer

2
Open Issues

• Single Line Extension
• One subscription relying on forking to N UAs vs.
  N-1 subscriptions without forking.
• Requires INVITE with Join primitive
• Call Park
• Park server returns extended sipfragso that
  SUBSCRIBE/NOTIFY not needed.

3
Open Issues Continued

• Call Pickup
• SUBSCRIBE/NOTIFY flows correct?
• Use of 481 to NOTIFY instead of SUBSCRIBE
  Expires0
• Auto Redial
• If B is a Gateway
• resource identified by Request-URI?
• Contact
• alan.johnston_at_wcom.com

4

• 2.10 Single Line Extension
• User A Forking Proxy User
  User User
• B1
  B2 B3
• 
  
• INVITE F1
  
• ---------------gt INVITE F2
  
• -------------gt
  
• INVITE F3
  
• --------------------gt
  
• INVITE F4
  
• ----------------------
  -----gt
• 100 Trying F5
  
• lt---------------180 Ringing F6
  
• lt-------------
  
• 180 Ringing F7
  
• lt---------------
  
• 480 Not Logged In
  F8

5

• 2.10 Single Line Extension (continued)
• User A Forking Proxy User
  User User
• B1
  B2 B3
• NOTIFY F20
  
• lt---------------------
  ------
• NOTIFY F21
  
• -------------gt
  
• NOTIFY F22
  
• --------------------gt
  
• NOTIFY F23
  
• ----------------------
  -----gt
• 200 OK F24
  
• lt-------------
  
• 200 OK F25
  
• ----------------------
  -----gt
• 200 OK F26
  
• lt--------------------
  
• 482 Loop
  Detected F27

6

• 2.16 Automatic Redial
• User A User B
• INVITE F1
• ---------------gt
• 486 Busy Here F2
• lt--------------- User B is busy
  
• ACK F3
• ---------------gt
• SUBSCRIBE F4
• ---------------gt
• 200 OK F5
• lt---------------
• NOTIFY F6
• lt---------------
• 200 OK F7
• ---------------gt