[asterisk-dev] New chan_iax media-only transfers: questions

[John Todd]

The code (deleted for brevity) below is really a great advance in 
IAX2 usage for anyone with a service-provider type network.  This 
allows billing to be managed centrally, while distributing media 
transcoding tasks to many remote machines - I've been hoping for this 
method for a few years.

However, there is still a catch. Let me pose some questions.  For 
terminology's sake, let's call the IAX system that sets up the call 
but steps out of the media path the "central" server, and the other 
two IAX2 stacks/media endpoints are the "caller" and "destination" 
systems.

   - is it possible for the central system to monitor or collect 
statistics on call quality during the call even though it is not in 
the media path?
   - I assume it is possible for the central server to request a 
hangup/transfer/hold of both sides via the Manager API... right?
   - do the caller and destination system know about each other as 
anything other than an IP address for media exchange?  (in other 
words, do they ever exchange IAX2 signalling directly, or is the 
exchange of messaging just a sub-set for media flow?)
   - does the destination" system know about the pre-existing call 
length (if any) that occurred before that call was received by them?

My questions above aren't necessarily important in my use of IAX, but 
it might be useful to understand how things work.  Sorry that I can't 
just read the code and get the answers myself; it's a bit dense in 
there for my humble C skills.

JT


(1) I think everyone knows my stance on encryption and privacy of 
communications, but I'm also aware that many organizations need to 
have CALEA compliance or at least call length/destination monitoring 
capability.




>Author: markster
>Date: Wed May 10 04:09:16 2006
>New Revision: 26314
>
>URL: http://svn.digium.com/view/asterisk?rev=26314&view=rev
>Log:
>Allow media to go directly between IAX endpoints while signalling still
>goes through the existing path.
>
>Modified:
>     trunk/channels/chan_iax2.c
>     trunk/channels/iax2.h
>     trunk/configs/iax.conf.sample
>     trunk/include/asterisk/utils.h
[snip]
>Modified: trunk/configs/iax.conf.sample
>URL: 
>http://svn.digium.com/view/asterisk/trunk/configs/iax.conf.sample?rev=26314&r1=26313&r2=26314&view=diff
>==============================================================================
>--- trunk/configs/iax.conf.sample (original)
>+++ trunk/configs/iax.conf.sample Wed May 10 04:09:16 2006
>@@ -343,7 +343,9 @@
>  ;secret=markpasswd
>  ;setvar=foo=bar
>  ;dbsecret=mysecrets/place	; Secrets can be stored in astdb, too
>-;notransfer=yes		; Disable IAX native transfer
>+;transfer=no		; Disable IAX native transfer
>+;transfer=mediaonly	; When doing IAX native transfers, transfer
>+			; only media stream
>  ;jitterbuffer=yes	; Override global setting an enable jitter buffer
>  ;			; for this user
>  ;callerid="Mark Spencer" <(256) 428-6275>
>
[snip]