Hi, I have 2 bria sip clients on iphone that support the silk and silk HD codec. It seems the best codec currently available. I want to use this while both are registered on the 3cx server. I know that 3cx does not support the silk codec, but I think as long as I have 2 clients and pbx delivers audio is not enabeled it should work (The normal codecs like g722 and g711 work fine between the 2 clients) However 3cx seems to force an other codec to the iphone bria clients eg g722 or g711. When I disable these in the bria sip clients so that only the silk codecs are allowed by the bria sip clients I get an error 406 (not acceptable) Attempt to reach <sip:10@XXXXXX;user=phone> failed. Reason: Not Acceptable HereReason Unknown Call to sip:10@XXXXXX has failed; Cause: 406 Not Acceptable; from IP:XXXXXXX:62745 Can somebody help. I figured that pbx delivers audio is not enabeled and reinvite is enabeled shoud do the trick but unfortunatly not.