[SIPForum-discussion] Would the fax call fail if there is a mistmatch between SDP Attributes

[mustafa aydin]

Hello Guys,

In my scenario, the receiving gateway sends a reinvite (to negotiate t38) with 
the following SDP attributes;

Media Attribute (a): T38FaxVersion:0
Media Attribute (a): T38FaxMaxBuffer:1100
Media Attribute (a): T38FaxMaxDatagram:612
Media Attribute (a): T38MaxBitRate:14400
Media Attribute (a): T38FaxRateManagement:transferredTCF
Media Attribute (a): T38FaxUdpEC:t38UDPRedundancy

However, the emitting  gateway responds only with the  attributes below in 200 
OK;

Media Attribute (a): T38FaxRateManagement:transferredTCF
Media Attribute (a): T38MaxBitRate:14400

Then the recieving gateway sends another reinvite with removing the 
"T38FaxUdpEC:t38UDPRedundancy" attribute, but this time the emitting gw responds 
with a 200 which has "0" at it`s image port.

My questions are; whether the mismatch between these attributes is a reason for 
a failure ? If so, should not  the emitting gw respond back with a failure 
message instead of a 200 OK ?  


"draft-mule-sip-t38callflows-02.txt" indicates that only T38FaxMaxBuffer  and 
T38FaxMaxDatagram are optional, does it mean that all other attributes must 
reside at the SDP ? 


Best Regards,
Mustafa Aydin


      
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