port configutaion for high load setup?

[Megamuch]

Hi guys,

I'm running into a 3cx box with 512 concurrent calls. All calls are going through a CFD app and out to an extension or external DID.
All looks good but I'm suspecting a possible port exhaustion for the default install.
IVR_RTPFIRST / IVR_RTPLAST now has 2000 ports available: 12.000 -> 13.999
TNL_IVRFIRST / LAST uses 14.000 - 14.999

FIRSTEXTPORT LASTEXTPORT 9.000 - 10.499

I'm wondering if these values should be altered given the call rate and call volume running through the box.

Does anybody know if these port ranges need to be widened up to support 512+ concurrent calls?

 

[NickD_3CX]

Before going onto explaining what ports the system uses, could you say why you suspect a port exhaustion? What symptom are you seeing.?

Each concurrent External call that negotiates only audio uses 2 ports (if video is negotiated it's 4 ports, but very rare for External calls from providers).
If you are forwarding the a call to a Remote STUN IP Phone extension (this does not apply for LAN/SBC extension), then another 2 (or 4) ports are used.

The above is counted as 1 SC, so the worst case scenario which is the above, each call could 'consume' 4 RTP Ports from the pool of 9000-10499.

If though the destination extension is a LAN/SBC IP Phone, or Windows/Mobile App, or WebClient, only 2 ports from this range is counted.

Tunnel and IVR ports I think are OK.

If you have a 512SC License, I find it difficult that you will have run out of ports, but if you open a ticket with the 3CX Support Team, they will be able to tell you if this is the case or not.

 

[Megamuch]

HI nick,

Thanks for replying.
I'm seeing some calls that are coming into the 3cx box with audio, through the CFD app and then we transfer out to external DID. The outbound call from 3CX is empty in terms of RTP. The call completes, but the audio stream is not there.

This seems to happen occasionally and only under high load.

We're running voipmonitor software in the network which sits between the 3cx box and our SBC's. We can clearly see audio coming in from sbc to 3cx but once we pass through the CFD app, the call leg is empty. so something is happening during the bridging of these calls causing the outbound leg to be flatlined / dead.

With regards to the port exhaustion:
My guess was:
1 inbound call to CFD app = port 5060 signalling + 1 rtp port
1 outbound call from CFD to external DID = port 5060 + 1 rtp port.

no tunneling or video or web / app integration used. Just plain old PBX -> IVR and back out to the PSTN.

 

[NickD_3CX]

I see, in that case, it may be advised to contact the 3CX Support Team, provide them with some logs when an occurrence appears of what you describe, then they can assess if more ports are required.

I wouldn't recommend making any changes yourself to the port ranges in case you accidentally use overlapping ports of another service, 3CX Support will tell you if this is the case, and if yes, how to adjust the values.