[Asterisk-Users] RC1 problem? (Conversation over two IAX2 streams = nasty, gappy audio)

[Andrew Kohlsmith]

Jeremy McNamara and I spent some time tonight figuring this out.

(aside: anyone claiming nufone doesn't have decent customer service is full of 
shit, who else is gonna spend over 3 hours helping a customer?)

The gappy audio problem isn't quite what I first thought:
It has nothing to do with IAX2, SIP does it too.
It has nothing to do with a specific codec.
It has *everything* to do with native bridging.

home* -IAX2- colo* -IAX2- switch-1.nufone.net

I am using xlite to home* but a zap interface does the same thing, the problem 
is with the native bridging between colo* and switch-1.

switch-1 runs RC1
colo* runs CVS HEAD 20040806 but also ran CVS HEAD 20040604 with the same 
problem.  The gappy audio problem started showing up around the time Nufone 
upgraded to RC1.

home* -> colo* GSM and colo* -> switch-1 GSM: dead audio (from nufone) 1:02 
into the conversation.  It stays dead for a good long time but the remote end 
can hear me (I was calling an IVR and hitting # every 10 seconds or so, it 
could hear me).

home* -> colo* GSM and colo* -> switch-1 iLBC or ULAW, no dead air.
home* -> colo* iLBC and colo* -> switch-1 iLBC, dead air 1:02 in.
home* -> colo* iLBC and colo* -> switch-1 ULAW, dead air 1:02 in.

seeing a pattern?  :-)

I've privately sent steve my debug log and a pcap dump of a sample 
conversation.

The conversation is about 6 minutes long and the bulk of it is dead air, 
starting at 1:02.  There are a few (maybe 3 or 4) very short (2s) bursts of 
audio from the remote end but mostly dead air.  

So it's gappy alright...  but very much so. Note that the gappy audio has 
changed a little as time went on.  When we first started seeing it (around 
the 20th of June or so) it resembled dropped packets or a congested link.  
Short bursts of silence or garbled audio.  The past few days it was getting 
to be two to three seconds of dead air and now tonight it dies 1:02 in and 
stays dead for a minute or two, then a burst of audio which quickly garbles 
(2s) and then silence for another minute or two.

The IVR I called through Nufone could hear my # key presses.  If I didn't hit 
anything the remote IVR would hang up after 20s or so.

Note that there are no native bridging problems to VoipJet.  They run 0.90 
apparently.

Again: nufone' s been great in helping diagnose this.  Highly recommended.

Regards,
Andrew