Asterisk saying "Invalid GSM Data"

I am slowly getting this Asterisk off the ground… I just configured a SNOM 200 phone to register with Asterisk - I have tried the test extension of 500 which dials the Asterisk demo at digium. When I try to respond to the menu choices, the demo does not respond to the button presses and on the console I get this message: “codec_gsm.c:177 gsmtolin_framein: Invalid GSM Data” each time I press a digit on the phone.

I checked google and found that someone else had the exact same problem but no one answered it.

Has anyone else come acros this and found a solution?



I got Asterisk to recognize the button pushes. I found the answer on the WIKI - here is what they proposed and it solved my problem - however the console still says “Invalid GSM Data” - but at least the button pushes are recognized.

"If you are having difficulties with your SNOM phone detecting tones that are entered from the keypad, try setting the DTMF Mode to rfc2833 in your sip.conf: