[SIPForum-discussion] Is the preference codec 0 ?

[Herve Jourdain]

Hi,

 

As the response provides only one codec, and it’s codec 0, then yes I think codec 0 has been successfully negotiated.

 

Regards,

 

Herve

 

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From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of ? ?
Sent: mercredi 27 août 2008 11:54
To: group SIP
Subject: [SIPForum-discussion] Is the preference codec 0 ?

 

Hi All, 

there is a call flow of modifying session between two different softswitch:

User A           User B    

|  RTP Established   |

|<=============>|     

                   |  INVITE [SDP]       |  the offer SDP m= audio 9256 RTP/ATP 8 0 97          

                   |------------------------>|            

                   |             100               |

                   |<------------------------|          

                   |                                   |

                   |       200 [SDP]          |  the answer SDP m= audio 10054 RTP/AVP 0

                   |<------------------------|            

                   |            ACK             |  

                   |------------------------>|    

 

Well, according to RFC3264, the preference codec should be present at first. So, the User A would like to choose PT=8 (PCMA), while the User B just afford PT=0 (PCMU). 

 

MY QUESTION IS:  Did they modify the session sucessfully? and if so, is the audio codec they  had negotiated  PT=0 (PCMU) ?  

 

 

Thanks & Regards

 

Nora

  

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