[Asterisk-Users] Amazing, great protocol IAX

[Thomas Hutton]

Hi;

I've just had a couple of discoveries in the learning process that are
really making me impressed with this software.  

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.  This
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.  

2) Absolute control over codecs and translations.  This took me a while
to understand how to force things to get translated.  I'd be curious to
know a couple of pointers on this subject - 

A) Which is better sound quality in this situation?
On a local net (100 megabit) my SIP phone talks to Asterisk running on
my firewall.  I only have 128K upload (sometimes) on my fricken
Third-World DSL connection so I want to use GSM or ILBC going out over
IAX2.  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?  I honestly can't tell a difference in
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.

B) I forgot what I was thinking for B, sorry about that.. lost my...

C) Going back to the possibility of losing CDRs, I can see another
possible time when a person would want to disable Native Transfer Mode -
when the IAX client is an IAXY box. (no way they write CDRs, let alone
cdr_postgres)  I'm still itching to try one of those things out -
anybody have good or bad experiences with them?

Thanks, much obliged,

Thomas Hutton