HandyTone 286 and Asterisk: DTMF
Last year, I bought me a Grandstream HandyTone 286 ATA to connect an ordinary phone through normal Ethernet with my Asterisk. I set up the box and sometimes a few things, e.g. DTMF did not work correctly. Today, I found the correct options for the device. Concerning DTMF you’ve the following choices in the setup page:
- via RTP
- via SIP-Info
Till now, I’ve selected SIP-INFO, then RTP. But in this case, the HandyTone needs to decode the DTMF frequencies to transmit the number through SIP. With the first option set, HandyTone does not care about DTMF; it just routes the audiostream to my Asterisk. The Handytone does not decode DTMF tones very well, therefore I need to send them “in-audio” and let Asterisk decode them. I need to tell Asterisk to decode the DTMF in the autostream by setting
dtmfmode = inband relaxdtmf = yes
in the sip.conf. This should work and will decode the DTMF tones successfully.