tyntec supports three different methods of transporting DTMF tones:

  • As SIP INFO requests (described in RFC 2976)
  • As telephone-event packets in the RTP stream (described in RFC 2833)
  • In-band as part of the audio stream (RTP) 

The in-band transmission method is the least recommended, because it is sensitive to audio compression and can only be used reliably in combination with G.711 (PCMA/PCMU). Please note that the list of supported methods may differ from country to country, when in doubt please consult with technical support.