Phones - Why is my Snom MP incorrectly sending DTMF via SIP?

Snom MP phones on firmware v.7.x may not send correct DTMF over SIP when configured with a phone feature pack.

The Snom MP phone has had a change done on the v.7 firmware and higher.  When configured with the feature pack the DTMF via SIP info setting is defaulted to NO.  Making changes to this when configured with a feature pack will not properly save, it reverts to the default setting.

If you manually register the phone using the snom web interface you can manually change the DTMF via SIP INFO setting to SIP INFO ONLY and DTMF will start to pass correctly.

The phone must be reset to factory defaults prior to logging into the menu which resets the user/password:

1. default user: admin

2. default password: admin or 0000