[Asterisk-Users] Amazing, great protocol IAX

[Benjamin on Asterisk Mailing Lists]

On Sun, 03 Oct 2004 22:04:46 -0300, Thomas Hutton <pres at nicheware.com> wrote:
> 
> 1) IAX transfer - I'm running Asterisk boxes A, B, and C.  B is in the
> middle and has a dialplan that points to extensions on C.  When a client
> on A in the proper context on B tries dialling a client of C, B is smart
> enough to release itself somehow from playing telephone in the middle,
> letting A and C network directly with each other.  This totally rocks.
> Who cares if it takes an extra 2 - 3 seconds to complete dialling.

It doesn't take any longer to dial. The transfer happens about 8-10
seconds into an already established call.

> is called Native Transfer Mode, no?  I don't see why anyone would want
> to disable it unless they were worried about missing CDR's - or hadn't
> figured out how to connect to a remote DB from A, C, or both.

In some cases where both B and C are behind a NAT, transfer will have
to be disabled because the hosts cannot see each other directly.

> Should I let the DSP in the phone talk to asterisk in ULAW or
> ALAW, having Asterisk translate to GSM or should I force the phone to do
> it in the lower bandwidth codec?

Depends on how limited your CPU capacity on the Asterisk server is. If
you run into CPU bottlenecks because of transcoding, then you are
better off to let the phone use the low bandwidth codec so Asterisk
can simply pass it through without doing transcoding.

> quality or latency.  I'm not real impressed with the Grandstream
> Handytone 286 because it doesn't have GSM - so I'm stuck trying to
> compare straight through ILBC to translated GSM.  Any fine tuning codec
> advice would be appreciated.

ILBC is definitely superior in sound quality to GSM.

rgds
benjk

-- 
Sunrise Telephone Systems, 9F Shibuya Daikyo Bldg., 1-13-5 Shibuya,
Tokyo, Japan.

NB: Spam filters in place. Messages unrelated to the * mailing lists
may get trashed.