Internal calls dropping 3 seconds after answering, receiving phone gets no audio

[lightspeedhosting]

• 3CX Version - 16.0.676 (running on VM in Chicago, Vultr)
• Using FQDN
• Phones being used: Yealink T54w with firmware version 96.84.0.35

I have an office we just did an install for. 12 phones and calling in from external works great, and calling external numbers and dialing out works fine.

But anytime an employee calls another employee using their four digit extension, the receiver gets the ring ,they pick up and the receiver and sender both cannot hear anything and 3CX drops the call within 3 seconds. This is ONLY happening for internal extension calling another internal extension.

One final note, if an internal employee calls another employee using their full DID then it works for about 30 seconds and drops. The issues with this installation ONLY seem to appear on internal calls and happens every time.

I have a pcap I captured during it, and I took a pcap from one of the phones as well to see if it had any other information.

 

[cobaltit]

Yep the Pi4 will eventually be the way to go but 3CX hasn't officially supported it yet. Understand your hesitation based on your recent experience but myself and many others here use Pi's with a good success rate. VM is definitely preferred if the infrastructure is in place but otherwise a Pi with a quality power supply, good SD card and small UPS works fine.

For redundancy you have a couple options. You can simply put in two Pi's and have half your phones point to one and the other have to the other. That's minimal effort and supported easily in the 3CX UI. IF one dies just re-point the other phones, re-provision and you're all set. If you are looking for something at little more bullet proof you have to setup DNS and SRV records.