El Martes, 9 de Febrero de 2010, Vikram Ragukumar escribió:
Could it be that this byte was appended somewhere downstream(possibly at the wireless router..) or can i be sure that the byte was added during SIP Message construction by the cellphone software ?
You cannot know it by just inspecting the request. You could be behind a fu***** SIP-ALG enabled router rewritting SIP requests "to fix the NAT".
You can get more information here: http://www.voip-info.org/wiki/view/Routers+SIP+ALG
To detect if you router has SIP-ALG enabled you can try various options:
1) Ensure you are not using STUN in your client so the request arriving to the proxy should contain client private address in Via and Contact header.
2) Try an utility I coded which detects if a host is behind a SIP-ALG enabled router: http://dev.sipdoc.net/wiki/sip-stuff/SIP-ALG-Detector