Chapter 10 The VoIP Account Screens

Table 76 SIP Call Progression (continued)

A

 

P

B

13. UPDATE

 

 

 

SE: 3600

 

 

 

------------------

>

 

 

 

 

 

 

 

 

14. UPDATE

 

 

 

SE:3600

 

 

 

----------------------->

-------------------->

 

 

 

 

 

 

 

15. OK

 

 

 

SE: 3600

 

 

<----------------------

<-------------------

 

 

 

 

16. OK

 

 

 

SE: 3600

 

 

 

<------------------

 

 

 

 

 

 

17. BYE

 

 

 

------------------

>

 

 

 

 

 

 

 

 

 

18. OK

 

 

 

<-------------------

 

 

 

 

1A sends a SIP INVITE request. This message is an invitation for B to participate in a SIP telephone call. A’s INVITE specifies a SE of 60 seconds.

2A’s request arrives at P but is below the minimum allowed value of 3600, so it is rejected with a 422 message, which contains the MSE of 3600.

3A sends an ACK to acknowledge the message was received.

4A retries the INVITE request with SE of 3600 and MSE of 3600.

5The SE in the new INVITE is acceptable so P forwards it to B.

6B receives the INVITE.

7B responds with an OK message which includes the SE of 3600.

8P forwards the OK message to A.

9A receives the OK.

10A then sends an ACK message to acknowledge that the call is established completely.

11The proxy server forwards the ACK message to B.

12Now A and B exchange voice media (talk).

13After around half of the SE time period is reached, or 1800 seconds in this case, A sends an UPDATE request to refresh the session.

 

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WiMAX Device Configuration User’s Guide