I have problems with sending DTMF, I have a Thomson ST2022 phone configured with DTMF inband, my provider requires inband so I think that the [ST2022] in sip.conf should be inband. this conf is ok with Asterisk voicemail and my provider VM but I cant access to my compagnie VM.
if I specify rfc2833 Prov VM & compagnie VM are ok but Asterisk VM does not work
I cant find any solution since many days, aliitle help may be usefull
Are you using G729 ? G729 + inband do not work to well.