[cisco-voip] DTMF fun

[Ryan Ratliff]

This won't be valid with out of band DTMF, and almost no Cisco devices actually support true in-band DTMF.  We will do out of band (MGCP Notify to H.245 Signal in his case) or RFC 2833 in band but you'll get nowhere fast trying to do true in-band DTMF with cisco voip devices.

-Ryan

On Jan 20, 2010, at 4:02 PM, Mark Holloway wrote:

Try G.711 and see if the issue persists.  If it doesn't persist it's because you are getting tone distortion on the IP network caused by a compressed codec.

On Jan 20, 2010, at 1:26 PM, Madziarczyk, Jonathan wrote:

> Maybe I'm not explaining myself correctly, or I don't understand how it
> works...most likely a combination of both.  The link between my CUCM and
> the PBX is not H323 to H323.  the PBX thinks the gateway is a DMS100
> link, the CUCM thinks the gateway is a H323 gateway.  So I don't know
> that the PBX is even capable of understanding H245 signaling, since it's
> getting it's DTMF inband at that point.  Does that sound correct?
> 
> Having said that I was able to run the debug h245 asn1 on my router,
> which does show me whether the DTMF is getting to the h323 gateway or
> not.  I guess then next logical step is to see if it is making it to the
> VM without being distorted to the point that VM cannot recognize it.
> 
> 
> 
> -----Original Message-----
> From: Rhodium [mailto:rhodium_uk at yahoo.co.uk] 
> Sent: Tuesday, January 19, 2010 5:04 PM
> To: VOIP Group; Madziarczyk, Jonathan
> Subject: Re: [cisco-voip] DTMF fun
> 
> The easiest point for me to start to troubleshoot this would be the
> gateway's H.323 connection to the PABX.
> 
> CUCM sends DTMF via H245 signal (accepting H245 alphanumeric [AN] only)
> so you need to determine what type of DTMF relay your PABX supports?
> Does it support H245 Signal or H245 AN.
> 
> You can run "debug h245 asn1" to see what type of relay is being used on
> the gateway (config dependent) and see whether all the digits are being
> sent to the PABX and received from the CUCM. If you are seeing the
> correct digits, then you know that the PABX is not accepting all the
> digits, if you are not seeing all the digits, the problem is between the
> PSTN and your gateway. 
> 
> HTH.
> 
> 
> 
> 
> 
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