[Asterisk-Users] DTMF crashes chan_capi

[Jamie Neil]

Hi,

I'm having a problem with DTMF tones from my SIP client apparently crashing
the chan_capi driver. However I'm not sure whether this is a bug or
misconfiguration on my part: if I set "softdtmf=1" in
/etc/asterisk/capi.conf the problem goes away. Does the AVM B1 not support
DTMF detection?

The set up I have is using latest CVS (3 days old) running RH8 on a 933MHz
P3. SIP client is SJPhone (G711) on Windows connected to * via a 100Mbit
switched LAN. PSTN connection is using latest chan_capi on an AVM B1 PCI v4
card (a steal at £1.20 on ebay :)).

I can call the * box using the SIP client and interact with the voicemail
app with no problems using in-band DTMF. I can also call in from the PSTN
through the capi interface and interact with the IVR menu with no problems.
Finally I can bridge the CAPI and SIP channels and hear DTMF digits entered
on the PSTN phone with no problems (they are also detected and displayed on
the console).

However when the CAPI and SIP channels are bridged, entering more than a
couple of DTMF digits into the _SIP_ client appears to crash the channel:
neither party gets disconnected, but there is no longer any audio in either
direction and new calls (inbound or outbound) trying to use the CAPI channel
fail. Once locked if I enter "capi info" in the * console it return nothing
and trying to autocomplete capi commands e.g. "capi [TAB]" just locks the
console up. Entering capiinfo and lsmod at the command prompt suggests the
driver is ok. The only way of getting it working again is to restart *.

When I switch to softdtmf, everything seems to work fine, but I noticed that
even though DTMF signalling works fine on the IVR menu, once the call is
bridged DTMF digits entered on the PSTN phone are not displayed on the
console like before.

Jamie Neil
Versado I.T. Services Ltd.