Issue with Delayed Audio at Beginning of Calls

[EddieW]

We have a client that has been having intermittent issues with delayed audio at the beginning of calls, both inbound and outbound, They have premise 3CX, v18.0.8.939, on a Windows server (VM), SIPTrunk.com for SIP trunks and a SonicWALL firewall. We have numerous other installs with the same setup and all are configured per their respective requirements. SIPTrunk.com is saying some calls are being setup on ports outside the RTP range 10000-10999 which I would think is their responsibility. Since it has been intermittent is has been difficult to get a packet capture of an example. Has anyone else encountered this audio delay at the beginning of calls, could be 10, 20 even 30 seconds and then there is audio and it is fine.

 

[SteveITS]

Pretty sure I've seen other posts over the years, FWIW. Is this with all devices? (app, web client, phone)