[asterisk-users] DTMF between sip trunks and PRIs

[James Lamanna]

Hi,
I'm looking for some advice on how to solve DTMF issues.
I have 2 boxes, one which is the connection to the PSTN (PSTN) through
PRIs and SIP trunks, and a second (PBX) which has UAs registered to
it.
We have a customer that has an existing pbx that we trunk analog lines
to using a GXW-4008.
The GXW is set to dtmfmode inband. This seems to provide the best outbound DTMF.

The issue I'm currently having is with inbound DTMF.
PBX and PSTN are connected through a standard sip trunk. Both machines
are on the same physical switch.

Here are the results I've seen:

PBX <-> PSTN using rfc2833 | Incoming call on PRI  | DTMF on pbx
voicemail system fails (dup/missing digits)
PBX <-> PSTN using inband | Incoming call on PRI  | DTMF on pbx
voicemail system is correct

PBX <-> PSTN using rfc2833 | Incoming call on SIP  | DTMF on pbx
voicemail system is correct
PBX <-> PSTN using inband | Incoming call on SIP  | DTMF on pbx
voicemail system is correct

All asterisk versions are 1.4.35.
PRI card is a Sangoma A104 with HW DTMF detection.

Does asterisk just have a problem converting the DTMF from the
D-channel to rfc2833?
The DTMF log looks ok (I dialed '642'), so I'm not sure where the
issue is coming in.


[Jul  4 21:05:44] DTMF[9769] channel.c: DTMF begin '6' received on Zap/15-1
[Jul  4 21:05:44] DTMF[9769] channel.c: DTMF begin passthrough '6' on Zap/15-1
[Jul  4 21:05:44] DTMF[9769] channel.c: DTMF end '6' received on
Zap/15-1, duration 100 ms
[Jul  4 21:05:44] DTMF[9769] channel.c: DTMF end accepted with begin
'6' on Zap/15-1
[Jul  4 21:05:44] DTMF[9769] channel.c: DTMF end passthrough '6' on Zap/15-1
[Jul  4 21:05:45] DTMF[9769] channel.c: DTMF begin '4' received on Zap/15-1
[Jul  4 21:05:45] DTMF[9769] channel.c: DTMF begin passthrough '4' on Zap/15-1
[Jul  4 21:05:45] DTMF[9769] channel.c: DTMF end '4' received on
Zap/15-1, duration 100 ms
[Jul  4 21:05:45] DTMF[9769] channel.c: DTMF end accepted with begin
'4' on Zap/15-1
[Jul  4 21:05:45] DTMF[9769] channel.c: DTMF end passthrough '4' on Zap/15-1
[Jul  4 21:05:45] DTMF[9769] channel.c: DTMF begin '2' received on Zap/15-1
[Jul  4 21:05:45] DTMF[9769] channel.c: DTMF begin passthrough '2' on Zap/15-1
[Jul  4 21:05:46] DTMF[9769] channel.c: DTMF end '2' received on
Zap/15-1, duration 100 ms
[Jul  4 21:05:46] DTMF[9769] channel.c: DTMF end accepted with begin
'2' on Zap/15-1
[Jul  4 21:05:46] DTMF[9769] channel.c: DTMF end passthrough '2' on Zap/15-1

Thanks.

-- James