[asterisk-users] pap2 - dtmf works when 'sip debug' is enabled

[James Harper]

> > I am having an odd problem with a linksys pap2 ata and asterisk...
> > Asterisk won't detect digits from it until I issue a 'sip debug'. As
> > soon as I turn on sip debugging, everything works perfectly (classic
> > heisenbug)!
> 
> Instead of SIP debug, try capturing the traffic with tcpdump etc. on
> the Asterisk server.  If even that is too invasive, connect the PAP2
> and a PC to the network via the same dumb hub (or managed switch);
> run wireshark on the PC to capture.
> 
> If you catch the PAP2 misbehaving, make sure you have the latest
> firmware for it.  If no luck, try setting DTMF Tx to AVT.  If still
> no luck (and your network speed and jitter permits), perhaps alaw
> codec with inband tones will work.

I tried the TCP dump (I was more concerned that it was a bug in Asterisk
though... see below) and found that my asterisk server was sending the
rtp packets to the pap2 via its internal address. This works because
there is a VPN (OpenVPN) between the two sites, but OpenVPN adds delay
(compression) and packet overhead so I preferred it to go externally.

I added in the 'external IP' setting to the PAP2 and set up all the
other NAT stuff and now it works great! Thanks for the hint.

I still think there is a bug in Asterisk - there should be no situation
where turning on debugging makes the problem go away (unless the problem
is _very_ timing sensitive, which wasn't the case here). But Debian Etch
is hardly the leading version of Asterisk and I'm not able to test a
later version at this point so I'll leave it be.

Thanks again

James