[cisco-voip] Early media

[Karl Smith]

Hi Bryan,
 
thanks for your suggestions. This morning I was just thinking exactly on the same lines. I have in fact performed the suggested debugs and confirmed that the gateway is infact cutting through the early media; it is the central office which is not switching it through to the caller. I have also traced the SS7 signalling (i have access to the CO signalling system) and the ACM lacks the optional parameter :
 
'Inband information: inband info or pattern now available'
 
Furthermore, looking at Q931 rec, it appears that not all ISDN networks supports the transmission of early media originating from the ISDN subscriber side:
 
K.2 Procedures
As a network option, completion of the transmission path prior to receipt of a call acceptance
indication may be provided in one of three ways:
a) on completion of successful channel negotiation at the destination interface; or
b) on receipt of a message containing an indication that in-band information is being provided;
or
c) not at all, i.e. this option is not supported by the network.
 
Thanks a lot for your help. 
 
Best regards,
 
Carmelo
 
 
 
 
 
 
It should be cut through dependent on the sip progress message we receive.
You might try 'progress setup enable 3' on the voip sip dial-peer as well.

Can you make a single test call with the following debug enabled so we can
see what is happening:
    - debug isdn q931
    - debug ccsip message
    - debug voip ccapi inout
Make sure that you have disabling console logging to minimize the impact of
enabling the debugs.

You can also check the output of 'show call active voice brief' while the
call is in alerting stage.  You should see on the ip call leg side the rx
packet count incrementing and on the telephony call leg side you should be
able to see the 'out' dbm level fluctuate when you do multiple iterations of
the command.  If you see what appears to be some audio on the telephony call
leg (meaning that you see the 'out' level at something than around -79dbm),
then it sounds like the audio is being cut through at the gateway but
somewhere in the isdn cloud it is not being cut through.

Bryan


From: Karl Smith <sipware at yahoo.co.uk>
Date: Tue, 12 Apr 2005 15:20:11 +0100 (BST)
To: <cisco-voip at puck.nether.net>
Subject: [cisco-voip] Early media

Hi,
 
thanks a lot for your help, but unfortunately the rtp send-recv did not
solve the problem. I have also upgraded the IOS but still no success.
 
Any other ideas??
 
Regards,
 
Carmelo
 
 
 
 
 
 
From: "Teodor Georgiev" <tgeorgiev at is-bg.net>
To: <cisco-voip at puck.nether.net>
Sent: Tuesday, April 12, 2005 15:42
Subject: Re: [cisco-voip] Early media

> 
> 
> voice rtp send-recv
> 
> issue that command in global configuration mode. It shall solve your problem.
> The issue you have described below is an usual behaviour - the reverse
> "bearer" path won't be opened until a CONNECT message is received.
> 
> 
> 
> On Tuesday 12 April 2005 11:40, Karl Smith wrote:
> > Hi,
> >
> > I am using a 2610 as a sip to isdn gateway. It appears that there is an
> > issue with early media. When the gateway receives rtp in early media on the
> > ip side it does not switch it through on the isdn bearer channel. Hence if
> > any announcements or tones are provided on a media server just after the
> > 183 session progress and before the 200 OK, these cannot be heard on the
> > ISDN side.
> >
> > This problem does not exist in the reverse direction; i.e. if an
> > anno! uncement is available on the isdn side before the connect message, the
> > gateway will swith it on an rtp stream and sends it to the ua.
> >
> > The IOS image that I am using is the c2600-is3x-mz.123-6b.bin
> >
> > Does any one knows whether this problem was resolved in more recent
> > releases? If yes, any ideas which release?
> >
> > Thanks and regards,
> >
> > Carmelo
> >
> >
> >
> > Send instant messages to your online friends http://uk.messenger.yahoo.com
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