I have three extension, I want them to ring when a call comes in, so I set a ring group to ring all, and they all ring at the same time. The issue that I am trying to solve is that when a call is not answer, the call is redirected to a voice mail extension, all good up to here, but when the caller is offered to press 0 to leave a message, the system reply saying that "this call cannot be completed, please try again later..." Now, if I disable the ring group and redirect the call to an extension, if the call is not answer, the caller is offer to leave a message, the caller press 0, then it works just fine. The log event shows the following: 19:27:56.952 [MS211000] C:12.1: 18.104.22.168:52888 is delivering DTMF using RTP payload (RFC2833). In-Band DTMF tone detection is disabled for this call segment. I am using Windows 7, IIS web server, and callcentric. I have checked and re-cheked the settings, so I am lost. Any help would be appreciated. Thank you. UPDATE: Someone else is having similar issue, it was suggested to restart the IIS service, I did that, but also I changed the net framework to 4.0, not sure is this fix the problem, now it works!