Garbled system prompts externally; internal is fine

[Mark U]

When calling in from the outside system prompts and call quality is spotty; like a bad cell phone signal. 3CX is hosted internally, and internal call quality and system prompts are perfectly clear. Firewall is a Fortigate 60E and the firewall test finds no problems. Internet connection is Spectrum fiber, 50x50, and speed tests confirm full speed usability. Anyone run into this before or have any ideas?

 

[Marari]

When calling in from the outside system prompts and call quality is spotty; like a bad cell phone signal. 3CX is hosted internally, and internal call quality and system prompts are perfectly clear. Firewall is a Fortigate 60E and the firewall test finds no problems. Internet connection is Spectrum fiber, 50x50, and speed tests confirm full speed usability. Anyone run into this before or have any ideas?

I've seen (heard?) a similar issue with a client that has a FortiGate. I presume you are running an on-premise PBX based on the fact that internal calls are clear and external calls are garbled.

Do the firewall check again. Make sure that the FortiGate is doing full-cone (one-to-one) NAT for the media ports (UDP 9000-10999).

 

[CentrexJ]

Is the ALG turned off on the Fortinet?

We have customers who use Fortinet 60C and 80D with 3CX on-prem and SIP trunk without any quality issues.

 

[leejor]

Did this just start, or has it always been this way?

What Codecs are you using? Is there a difference between what's used on the trunks, and set to set?

 

[cobaltit]

Hyper-V VM by any chance?