asterisk users - Mar 2004 - Codec Translation Problem on IAX Softphones - Incoming Only

This is my first post to the list, and while I am sorry that
I have a problem that I need to bring to the list, I have
been a very satisfied reader/lurker on the list, which has
saved me from asking lots of questions so far :-).

Apologies in advance for the length...

I am new to *, but am already hooked, and have a reasonably
complicated setup working nearly perfectly. I have three
separate * servers under my control. One is on a static
publically available server (no boards in it, so it's more
like a "switch"). The other two are behind NAT'ed routers,
and each have two Digium X100P cards in them, with Sipura
2000 connected to the phones for each card. I have ITSP
accounts for outgoing with VoicePulse and NuFone as well.

I never know where I am going to be, so I set up the servers
for multiple ringing. If a call comes in to any of the three
* servers, the appropriate line(s) ring in all locations at
the same time. This works fantastically well.

In addition to this, I badly want to use an IAX softphone as
well, since I already stare at my laptop screen for 12+
hours every day, with a headset on (listening to MP3s :-),
so it would take less time to answer the call on the laptop
than to switch headsets to the phone.

Now to the problem...

If I use Sipura connected phones, everything works
flawlessly, every time. If I initiate a call from the
softphone (my current favorite is DIAX, latest version),
then all is fine as well. I get in trouble if I _answer_ a
call with any IAX softphone, that came in on a "real" Zap
channel. It's most definitely a codec translation problem,
but I can dial _out_ from DIAX via a Zap channel, and have
that call answered and be able to communicate, so I'm not
sure exactly what the problem is.

First, the specific error:

Mar 8 18:03:20 NOTICE[1209277232]: channel.c:1097 ast_read:
Dropping incompatible voice frame on IAX2[apartment]/4 of
format GSM since our native format has changed to ULAW

I get hundreds of these in rapid succession until I kill the
call.

Just to pendatically repeat myself, the same exact devices
work fine if DIAX initiates the call (even if it ends up
passing over a real Zap channel to the Sipura), and if the
Sipura initiates the call and DIAX picks it up, the above is
the error.

Here are the relevant sections of the iax.conf file:

[general]
port=5036
bandwidth=high
disallow=all
allow=ulaw
allow=alaw
allow=gsm
allow=iLBC
tos=lowdelay

;
; Connect to the apartment * server
;
[apartment]
context=apartment-in
type=friend
host=apartment.XXXXX.com
secret=mysecret
auth=md5

[hadar]
type=friend
context=from-hadar
secret=mysecret
auth=md5
host=dynamic
callerid="Hadar Pedhazur" <(XXX) XXX-XXXX>
mailbox=100

In the "apartment" server iax.conf file, I have an identical
set of declarations in the [general] section, and nearly
identical sections for the devices there (meaning, no one is
overriding the codecs defined in general). I have played
with a number of permutations of playing with the codecs in
general as well as the individual ones, and the above works
best for everything except a call _answered_ by DIAX.

Any pointers would be greatly appreciated!

Philipp von Klitzing was kind enough to send the solution to me off 
list, and I want to save others from responding as well, since his 
solution worked! Here's what he wrote:

      Add this to the [hadar] context and reload the server:

      disallow=all
      allow=gsm

Only after seeing this, did I realize how obvious it is. Clearly, the 
IAX softphones can only handle GSM, and by not overriding the default 
setting of allowing ulaw, I was telling * that it was OK to change the 
format from GSM to ULAW since the Sipura wanted ULAW. Doh.

On a separate note, I was having trouble getting cut off after 20-30 
seconds on calls from DIAX to other IAX2 servers, but not from my hard 
phones connected via Sipuras. A quick google of the list solved that 
problem too, by adding:

      notransfer=yes

to the same context above. I think that's because my softphone is 
behind NAT, on the same segment that another * server is behind NAT as 
well, or something similar to that. Anyway, all is right with the 
world again :-)

Thanks Philipp!

-----------------------------------------------------------------

Lots of snipping, just summary problem and conf files left in...

Hadar Pedhazur wrote:
> Just to pendatically repeat myself, the same exact devices
> work fine if DIAX initiates the call (even if it ends up
> passing over a real Zap channel to the Sipura), and if the
> Sipura initiates the call and DIAX picks it up, the above is
> the error.
> 
> Here are the relevant sections of the iax.conf file:
> 
> [general]
> port=5036
> bandwidth=high
> disallow=all
> allow=ulaw
> allow=alaw
> allow=gsm
> allow=iLBC
> tos=lowdelay
> 
> ;
> ; Connect to the apartment * server
> ;
> [apartment]
> context=apartment-in
> type=friend
> host=apartment.XXXXX.com
> secret=mysecret
> auth=md5
> 
> [hadar]
> type=friend
> context=from-hadar
> secret=mysecret
> auth=md5
> host=dynamic
> callerid="Hadar Pedhazur" <(XXX) XXX-XXXX>
> mailbox=100
> 
> In the "apartment" server iax.conf file, I have an identical
> set of declarations in the [general] section, and nearly
> identical sections for the devices there (meaning, no one is
> overriding the codecs defined in general). I have played
> with a number of permutations of playing with the codecs in
> general as well as the individual ones, and the above works
> best for everything except a call _answered_ by DIAX.
> 
> Any pointers would be greatly appreciated!