I have done some testing on dialed digits uning a redial funcion , and I have noted that the IP Tel server sometimes interprets a double digit when only a single digit is dialed. I have seen this problem on different User agents and it can be most annoying connecting frequently to the wrong number.
I have confirmed what is happening through thje IP Tel call logs, and on one number it often displayed that a double 9 was dialed when it was a single 9
I have tried most possible DTMF modes, however The Voice mail is dependent on RFC2833 so I have focused my attention on that and explicitly set it in the extension as RFC2833. I have also tried passing and suppressing inband DTMF.