DTMF Issues

From reading around, it sounds like rfc2833 is the preferred DTMF mode. However, in this mode, my snom320 phones and asterisk 1.4.4 don’t want to place nicely.

If I dial my voicemail extension, and then punch in my password (“999” for example), the console will show “Incorrect Password ‘9999999999999999999’ for user…”. Then sometimes, it won’t even recognize any digits I punch in. And when I do make it into voicemail, half the time it doesn’t recognize my menu selections.

Should I just switch to inband and disable GSM in my sip.conf?

Please check how is your phone configured in regards to DTMF.
Post the corresponding part of users.conf (or sip.conf) there this snom’s extension is defined.
Post the global DTMF setting from your sip.conf