On inbound calls over PSTN with a Sangoma A200, sometimes the dtmf sequence is not decoded properly. Specifically, when dialing 20 or 21, sometimes it results in a call to 22. The reverse has not been observed. I thought that maybe there was an echo issue where the first character was repeated. But testing by pressing only 2 never seemed to result in a 22. It seems to be worse during the beginning of an outgoing message. This is Elastix 1.3. Any ideas?