These holidays I got an observation from one of my customers. His carrier claims that PDD was variable with some 6-second peaks. Although 6 seconds I believe it is not that critical, it is in the annoying area. Usually, 3-4 seconds are acceptable.
First, I will define what is PDD. From: NICC ND 1704 V1.2.2 2009-05 End-to-End Network Performance Rules & Objectives for the Interconnection of NGNs
For SIP the PDD would be the time from Sending the INVITE to receiving the first ringing response for example: an SIP/2.0 180 Ringing response.
Before starting to explain where to look at, and what you may do, I will explain the flow information. If you are using FusionPBX (and FreeSWITCH of course) with my RPM's or with the vanilla installer, it is most likely you are using a database backend.
Usually, when a call starts (it does not matter if it is from extension or from PSTN), with FusionPBX it follows this path:
Short answer yes. The more complex is your call flow, possible bottlenecks you have. The last example showed a stand-alone FusionPBX server, in which I can identify the following bottlenecks:
If you are in a high availability or load balanced environment, the call flow is much more complex and the database interaction more intense.
If you are using a database cluster, you need to see what I/O impact does your database have.
Here there are some actions I would suggest based on my experience:
If you put a dial-plan that does a pre_answer action when hitting the server, this will send the RINGING signal back to the origin without waiting that the destination is reached or not. However, this might backfire:
I suggest you go for the actions and use the workaround as the last resource.
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