asterisk users - Sep 2004 - allowing/disallowing codecs in dialplan?

Hi all,

Is there a possibility to set the codecs Asterisk will choose in the dialplan
("exten=>" statements or their contexts) instead of sip.conf?

My problem is that I connect my SIP phone with several providers (Nikotel,
Sipgate, Stanaphone) for icoming and outgoing calls. Not all of these providers
offer the same set of codecs. I'd like Asterisk to use the same codec for
the
provider side as well as of the device side, to prevent codec translation.
Unfortunately, Asterisk seems to negotiate the codec for the device and for the
peer independently, so it often happens it sets them differently.

I could of course just allow ulaw, bit I'd like to use ilbc where possible
(less
dropouts). So, I'd like to configure Asterisk in a way that, depending on
what
extension is chosen, it negotiates another codec with the phone. Of course I
considered setting the allow statements in the sections of sip.conf. But it
seems these settings are only considered on incoming calls, but not on outgoing
calls (initiated by a Dial application with the sip.conf section as its
argument).

So, when I have something like 

[general]
disallow=all
allow=alaw
allow=ulaw
allow=ilbc

[SipgateAccount]
type=friend
...
disallow=all
allow=ilbc

then these settings are only considered when I get an incoming call, but not
when I make an outgoing call using
"exten=>...,Dial/SIP/${EXTEN}@SipgateAccount,60,)"

Thanks in advance, Andy

-- 

Andreas Greulich
E-Mail: andreas.greulich@spl.ch
Skype: klaymen-neverhood

Sermo datur cunctis, animi sapientia paucis.

You said what is possible and in exists.
Can you try with the settings what you have mentioned.

-Kannaiyan

----- Original Message ----- 
From: "Andreas Greulich" <andreas.greulich@spl.ch>
To: "Asterisk-Users" <asterisk-users@lists.digium.com>
Cc: "Greulich, Andreas" <dust@triton.ch>
Sent: Monday, September 13, 2004 8:35 PM
Subject: [Asterisk-Users] allowing/disallowing codecs in dialplan?


Hi all,

Is there a possibility to set the codecs Asterisk will choose in the 
dialplan
("exten=>" statements or their contexts) instead of sip.conf?

My problem is that I connect my SIP phone with several providers (Nikotel,
Sipgate, Stanaphone) for icoming and outgoing calls. Not all of these 
providers
offer the same set of codecs. I'd like Asterisk to use the same codec for 
the
provider side as well as of the device side, to prevent codec translation.
Unfortunately, Asterisk seems to negotiate the codec for the device and for 
the
peer independently, so it often happens it sets them differently.

I could of course just allow ulaw, bit I'd like to use ilbc where possible 
(less
dropouts). So, I'd like to configure Asterisk in a way that, depending on 
what
extension is chosen, it negotiates another codec with the phone. Of course I
considered setting the allow statements in the sections of sip.conf. But it
seems these settings are only considered on incoming calls, but not on 
outgoing
calls (initiated by a Dial application with the sip.conf section as its 
argument).

So, when I have something like

[general]
disallow=all
allow=alaw
allow=ulaw
allow=ilbc

[SipgateAccount]
type=friend
...
disallow=all
allow=ilbc

then these settings are only considered when I get an incoming call, but not
when I make an outgoing call using
"exten=>...,Dial/SIP/${EXTEN}@SipgateAccount,60,)"

Thanks in advance, Andy

-- 

Andreas Greulich
E-Mail: andreas.greulich@spl.ch
Skype: klaymen-neverhood

Sermo datur cunctis, animi sapientia paucis.

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Hmm, I think the settings in sip.conf alone are not sufficient for what I look
for. Maybe I should be more precise to explain the problem.

When I make an outgoing call from my GrandStream (GS below) phone, I use a
prefix to differ between server A and server B (both PSTN gateways). A only
supports ULAW, B only supports iLBC (to make it easier :-). The diagram below
shows 2 outgoing calls, one to A, and one to B. For each there's the line in
the
config files mentioned:
              

   sip.conf:
    [GS]
    allow=ilbc ; cannot differ between server A
    allow=ulaw ; and server B here            <ULAW>
   extensions.conf:               +-----------------------------> Server A   
    exten => _1.,2,Dial(..@A,60,) | sip.conf: [A]
   ------------------------->-+---+           disallow=ilbc
         <ULAW> ???           |   |           allow=ulaw
GS                            | * |
         <iLBC> ???           |   |
   ------------------------->-+---+
   extensions.conf:               |           <iLBC>
    exten => _2.,2,Dial(..@A,60,) +-----------------------------> Server B
                                   sip.conf: [B]
                                             disallow=ulaw
                                             allow=ilbc

In sip.conf, I can only influence the righthandside negotiation. The
lefthandside negotiation between GS and * is only influenced by the [GS] section
of sip.conf, but of course the same for each outgoing call and will, say, always
chose ilbc. I miss the possibility that asterisk can negotiate with GS the ulaw
codec if GS dials a _1. number, and the ilbc codec if the GS dials a _2. number.
These difference could only be made in extensions.conf (dialplan), as they both
refer to the same section in sip.conf.

Now I'm aware that, technically, * probably already negotiated the codec
with GS
when it starts matchinf the dialplan patterns. But on the other hand, all needed
information (number the device wants to dial) should already be present in the
initial INVITE message from GS... so I wonder if there's any way to
influence
the codec negotiation depending on headers present in the initial SIP INVITE
message? Maybe this would require some code change, which would also be ok for
me.

Am I really the only person who wants to do something like above scenario and
avoid codec translation...???

Note that, of course, the same problem happens on incoming calls:




   sip.conf:
    [GS]
    allow=ilbc ; cannot differ between server A
    allow=ulaw ; and server B here            <ULAW>
   extensions.conf:               +-<--------------------------- Server A   
    exten => A,2,Dial(..@GS,60, ) | sip.conf: [A]
   <--------------------------+---+           disallow=ilbc
         <ULAW> ???           |   |           allow=ulaw
GS                            | * |
         <iLBC> ???           |   |
   <--------------------------+---+
   extensions.conf:               |           <iLBC>
    exten => B,2,Dial(..@GS,60,)  +-<--------------------------- Server B
                                   sip.conf: [B]
                                             disallow=ulaw
                                             allow=ilbc




----- Original Message ----- "Kannaiyan Natesan"
<nkans@speak2world.com>

You said what is possible and in exists.
Can you try with the settings what you have mentioned.


-Kannaiyan

----- Original Message ----- From: "Andreas Greulich"
<andreas.greulich@spl.ch>
To: "Asterisk-Users" <asterisk-users@lists.digium.com>
Cc: "Greulich, Andreas" <dust@triton.ch>
Sent: Monday, September 13, 2004 8:35 PM
Subject: [Asterisk-Users] allowing/disallowing codecs in dialplan?


Hi all,

Is there a possibility to set the codecs Asterisk will choose in the dialplan
("exten=>" statements or their contexts) instead of sip.conf?

My problem is that I connect my SIP phone with several providers (Nikotel,
Sipgate, Stanaphone) for icoming and outgoing calls. Not all of these providers
offer the same set of codecs. I'd like Asterisk to use the same codec for
the
provider side as well as of the device side, to prevent codec translation.
Unfortunately, Asterisk seems to negotiate the codec for the device and for the
peer independently, so it often happens it sets them differently.
...