[Freeswitch-users] Inband DTMF Problem

Michael Jerris mike at jerris.com
Thu Nov 6 07:25:26 PST 2008

On Nov 6, 2008, at 10:08 AM, Klaus Teller wrote:

> OK. I updated and tried flushing the DTMFs before playing the  
> commands and it works. Thanks.
> Now, i feel there is a more general issue of scalability around DTMF  
> (both inband as well as RFC2833) handling in Freeswitch. What do you  
> guys think?
> What i've been working on is a tool for testing voice applications.  
> The tool connects via Freeswitch to the voice platform and simulates  
> the behavior of the user. We've tried the tool with the most  
> reliable voice platforms out there as well as with some less reliable.
> What we observe is that in all cases, we can run 100 calls  
> sequentially without problem. But as soon as we have 10 calls in  
> parallel, digits start to get lost. Is this something you think  
> should be expected?
> I must note that there are a lot of DTMF reading and sending going  
> on. In fact, the testing tool doesn't use voice recognition to  
> assert whether the voice application is in the right state or not.  
> Instead, we instrument the voice application to emit some DTMF  
> sequences that are uniquely mapped to prompts. So there DTMF  
> sequences are read by the testing tool to determine if the voice app  
> is in the right state or not.
> Looking forward to your feedback.
> Klaus.

You should have no expectation whatsoever that inband dtmf will ever  
scale, as for rfc2833, I tend to doubt that there is any scaling  
issues there.  Do you have any traces and accompanying freeswitch  
debug logs that show this behavior?  Is it reliably reproducible?


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