[Asterisk-Users] IAX Jitterbuffer and trunking

[Richard Scobie]

Is there a way to configure the IAX jitterbuffer to get the benefit of 
trunktimestamps, while not having any jitterbuffering (reducing delay)?

My SVN asterisk systems use the following topologies:

1) PolycomSIP -> *1 ->IAX-> *2 -> H323 Gateway

2) PolycomSIP -> *1 ->IAX-> *3 -> Zap TDM400 Analog

3) H323 Gateway -> *2 ->IAX-> *3 -> Zap TDM400 Analog

In all the above, the primary jitter path is the IAX one and the codec 
is Alaw all the way.

In an effort to reduce path delay and multiple jitterbuffering I have 
configured the following:

On the basis that the Polycom IP500 phones have a decent jitterbuffer 
built in, Asterisk 1 has jitterbuffer=no in iax.conf.

Asterisk 2 has the same setting as the H323 GW has it's own jitterbuffer.

Asterisk 3 has jitterbuffer=yes in iax.conf, to buffer the Zap interface 
and provide PLC. I notice that zapata.conf has an entry jitterbuffers=4 
by default - is this a different one in which case should it be turned 
off or is it setting parameters for the IAX JB?

Looking at README.jitterbuffer:

"If you don't use trunktimestamps, there's lots of ways the jitterbuffer 
can get confused because timestamps aren't necessarily sent through the 
trunk correctly."

This presumably means that if I want to use IAX trunking effectively, I 
have to enable the IAX JB on all Asterisks.

Thanks,

Richard