Attached is a sip trace (from QA) for a call hold ( with MOH) and resume operation which results in no voice path after resume. Problem reported is that after the call resume there is no media path. Looking at the pcap, the ITSP sends G729 whereas sipx sends the ITSP G711 ( asymmetric meida ).
Note that on the re-INVITE (with SDP), sipX sends the ITSP all supported codecs (including G729 - I need to filter this out but that is a different problem ). The phone selects G711 and ITSP sends in G711 in the period of time following Frame 46. This is legal ( the ITSP answered with G711 and G729) However, it appears that the asymmetry of the media stream causes the observed problem of no speech path. So there appears to be an ITSP issue at hand. The asymmetric codec problem can be resolved again by sipxbridge restricting all re-INVITEs responses to to that codec negotiated for the FIRST call setup. This seems quite restrictive however and clearly the RFC allows for multiple codecs in the response to that re-INVITE but there is no speech path. So I am wondering if I should implement a single codec restriction on the re-INVITE response to avoid the situation. Thanks in advance for your help. Regards, Ranga -- M. Ranganathan
merged.xml.gz
Description: GNU Zip compressed data
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