[asterisk-users] DTMF detection on dahdi with b4xxp (again, some more details)

[Christian Theune]

Hi,

I tried again getting DTMF detection on my ISDN devices with dahdi going 
again. I used the channel debug to see whether asterisk sees the frames 
and detects them as DTMF.

Interestingly here's what works:

1. GSM phone -> chan_dahdi g1 -> asterisk -> can_sip -> SIP phone

Both the GSM phone and the SIP phone can issue DTMF that will be 
detected as features (transfer)

2. GSM phone -> chan_dahdi g1 -> asterisk -> chan_dahdi g4 -> ISDN phone

The GSM phone can issue DTMF that will be detected. The ISDN phone 
won't. (That's my issue.) I don't see any messages of asterisk 
recognizing the DTMF frames when pressing the keys. I do hear the DMTF 
sound on both phones.

3. ISDN phone -> chan_dahdi g4 -> asterisk -> chan_dahdi g1 -> GSM phone

The ISDN phone can issue DTMF that will be recognized and so does the 
GSM phone.

So. When the ISDN phone is receiving a call on g4 its DTMF sounds won't 
be recognized. OTOH when the GSM phone on g1 is being called it's sounds 
are recognized.

Sounds like a configuration issue to me. Does anybody have an idea what 
to look out for?

Thanks in advance,
Christian

-- 
Christian Theune · ct at gocept.com
gocept gmbh & co. kg · forsterstraße 29 · 06112 halle (saale) · germany
http://gocept.com · tel +49 345 1229889 0 · fax +49 345 1229889 1
Zope and Plone consulting and development