Double digits show up in the log

FreePBX version CentOS

When I call DISA from external SIP trunk. I get double digits. If I call from my cell to the main number and then answer the phone and press keys on my cell I can hear fast double tones. If I call my Land line from my cell, those double tones do not exist. I have a feeling that it has something to do with codacs and how they handle the tones. Can some one help ?