Hello,
I’m having repeated DTMF problems when attempting to join audio conferences like webex. The far side indicates that either the digit isn’t picked up or it gets repeated. I’ve played with various settings over several months and haven’t had any luck in finding a solution. Can anyone offer suggestions or areas to look for further troubleshooting or switches to flip, or even a magic bullet? 
The set up has both Grandstream GXP-2000s, Cisco SPA-301s and Linksys SPA3000 (or 3100) going to a dedicated Dell server running a Digium card and asterisk. I currently have the GXP2000 set at RFC2833 for DTMF and the sip.conf set at dtmfmode=auto. Asterisk version is 1.8.1.1 (it happened with older versions as well). I don’t believe network is to blame, ping times are sub-millisecond to the server and server’s load average is 0.00 across all time slots.
It happens whether I dial the conference code fast (short duration digits ) or slow, holding each digit.
Here are some logs, can provide more if appropriate.
1-000000dc
[Sep 1 15:32:31] DTMF[20959] channel.c: DTMF begin passthrough ‘7’ on SIP/gxpsteve1-000000dc
[Sep 1 15:32:32] DTMF[20959] channel.c: DTMF end ‘7’ received on SIP/gxpsteve1-000000dc, duration 670 ms
[Sep 1 15:32:32] DTMF[20959] channel.c: DTMF end accepted with begin ‘7’ on SIP/gxpsteve1-000000dc
[Sep 1 15:32:32] DTMF[20959] channel.c: DTMF end passthrough ‘7’ on SIP/gxpsteve1-000000dc
[Sep 1 15:32:32] DTMF[20959] channel.c: DTMF begin ‘7’ received on SIP/gxpsteve1-000000dc
[Sep 1 15:32:32] DTMF[20959] channel.c: DTMF begin passthrough ‘7’ on SIP/gxpsteve1-000000dc
[Sep 1 15:32:32] DTMF[20959] channel.c: DTMF end ‘7’ received on SIP/gxpsteve1-000000dc, duration 0 ms
[Sep 1 15:32:32] DTMF[20959] channel.c: DTMF end accepted with begin ‘7’ on SIP/gxpsteve1-000000dc
[Sep 1 15:32:32] DTMF[20959] channel.c: DTMF end ‘7’ detected to have actual duration 20 on the wire, emulation will be triggered on SIP/gxpsteve1-000000dc
[Sep 1 15:32:32] DTMF[20959] channel.c: DTMF end ‘7’ has duration 20 but want minimum 80, emulating on SIP/gxpsteve1-000000dc
[Sep 1 15:32:32] DTMF[20959] channel.c: DTMF end emulation of ‘7’ queued on SIP/gxpsteve1-000000dc
[Sep 1 15:32:33] DTMF[20959] channel.c: DTMF begin ‘8’ received on SIP/gxpsteve1-000000dc
[Sep 1 15:32:33] DTMF[20959] channel.c: DTMF begin passthrough ‘8’ on SIP/gxpsteve1-000000dc
[Sep 1 15:32:33] DTMF[20959] channel.c: DTMF end ‘8’ received on SIP/gxpsteve1-000000dc, duration 580 ms
[Sep 1 15:32:33] DTMF[20959] channel.c: DTMF end accepted with begin ‘8’ on SIP/gxpsteve1-000000dc
[Sep 1 15:32:33] DTMF[20959] channel.c: DTMF end passthrough ‘8’ on SIP/gxpsteve1-000000dc
[Sep 1 15:32:33] DTMF[20959] channel.c: DTMF begin ‘8’ received on SIP/gxpsteve1-000000dc
[Sep 1 15:32:33] DTMF[20959] channel.c: DTMF begin ignored ‘8’ on SIP/gxpsteve1-000000dc
[Sep 1 15:32:33] DTMF[20959] channel.c: DTMF end ‘8’ received on SIP/gxpsteve1-000000dc, duration 0 ms
[Sep 1 15:32:33] DTMF[20959] channel.c: DTMF begin emulation of ‘8’ with duration 100