mrengert

Hi - I am seeing problems with call hold (specifically the ExpressTalk softphone being put on hold) regarding the SDP session version number in the response to the INVITE for the hold operation (the 2nd offer) being incremented by 2 from the response to the original INVITE instead of by 1 as specified in RFC 3264 section 8. In fact it looks like the version number is always incremented by 2 anytime the SDP data changes, when the specification says it should be incremented by 1. This seems to cause problems with some SIP back-to-back user agents. Other phones (Grandstream BT-100 and snom 320) follow the specification. Anyone know if this is a bug in ExpressTalk, or if there is a setting that affects it? - Thanks

Hi - I also had this problem and have a back-door workaround, but it assumes you are running IMS on Windows XP. There is a file called "hosts" in the WINDOWS\system32\drivers\etc directory. This contains a list of IP lookups that are checked first before attempting a network DNS lookup. I found that the IMS was attempting to use the address "stun.fwdnet.net" for STUN, so I added an entry to the "hosts" file to redirect this address to the local host 127.0.0.1 as follows: 127.0.0.1 stun.fwdnet.net After restarting Windows (not sure this is strictly necessary, but it probably is) then the IMS when starting up no longer attempts STUN but simply performs a SIP REGISTER to the extension server IP as defined in the VOIP settings menu. Hope this helps...