Hi, I'm Currently using: 3CX Phone System Version5.1.4128.0 Free VOIP: Broadvoice There is a Broadvoice setting that I cannot change : DTMF: rfc2833 if available, fail over to InBand if rfc2833 not supported Is there a way to disable rfc2833 within the 3cx system? I am only using Codecs G.711 U-law and G.711 A-law as they support In-Band DTMF. My problem is I'm using another software PBX (CallButler for IVR) and it doesn't seem to like DTMF via rfc2833. If I connect CallButler (PBX) directory to my Broadvoice account then everything works great. If I connect my VOIP to 3cx and forward to CallButler tones are not recognized by CallButler. I'm presented with the following 3cx server status log [MS211000] C:1.1: 18.104.22.168:38410 is delivering DTMF using RTP payload (RFC2833). In-Band DTMF tone detection is disabled for this call segment. I have found a config file in the 3cx install directory: 3CXPhoneSystem.ini In the file there is an entry as listed below msAddRFC2833ForInbandDTMF=1 Can that value be changed to disable rfc2833? I feel that if I can get the 3cx PBX to tell Broadvoice that it does not accept DTMF out of band then Broadvoice will send in-band. Currently this appears to be a limitation of my VOIP provider and that of the CallButler PBX. I have contacted them both about DTMF via rfc2833. I'm hoping that 3cx PBX in the middle can solve the problem by simply telling Broadvoice that is does not accept DTMF via rfc2833.