[VoiceOps] Call established before audio path

Ryan Delgrosso ryandelgrosso at gmail.com
Fri Jun 13 12:40:52 EDT 2014

Ive seen this pretty regularly, often times it happens when there are 
multiple sip servers in the path, and the final 200ok with SDP takes a 
second to get to the endpoint. Especially when something that does 
symmetric latching is in the path. Its not uncommon for symmetric 
latching to cause this as the called audio will start flowing the moment 
it sends the 200ok, but the 200ok still has to be received by the caller 
and it has to begin sending audio for the latch to take and have the 
audio routed both ways.

The answer is typically a 0.5 second delay at the start of your prompt 
to insulate against this.

On 6/13/2014 9:07 AM, Brian Taylor wrote:
> We have customers who are reporting that when people call into them 
> that the beginning of the greeting is not being heard.
> It appears that the phones think the call is ready before there is a 
> complete audio path. We see this the most on calls that come in from 
> the PSTN. Long distance or toll free calls are the worst.
> We have a Broadworks system that uses Lucent 5010 (Telica) switches 
> for the connections to the PSTN.
> The symptom seems to be very similar for all of our PSTN connections, 
> to multiple carriers.
> I'm just curious if anyone has any experience with this problem, or if 
> anyone has any suggestions to get to the bottom of the issue.
> Any assistance or inspiration would be greatly appreciated.
> Thank you,
> Brian Taylor
> Socket Telecom, LLC
> brian at socket.net
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