FreePBX Total Channel Limits

Is there any kind of limit for total channels in FreePBX? I know that asterisk out of the box doesnt have any limits, , although obviously network capacity, processor capacity, etc. will limit things. My SIP trunk is mainly for inbound and outbound calls which can only have max of 8 anyway, but i’m wondering if there is any limits for total amount of simultaneous internal calls on FreePBX?


FreePBX doesn’t process the calls, just writes the dialplans. It has no limits per se

If you are asking about the practical limits of Asterisk:

  1. If you use re-invite, so audio passes directly between the endpoints, you can have thousands of concurrent calls, though you are probably limited to a few tens of new calls per second.

  2. If you don’t use re-invite, but Asterisk merely bridges the media with no processing, the limit is in the hundreds, depending on server speed, network bandwidth, memory, etc.

  3. If Asterisk has to transcode, record the calls, listen for DTMF commands, etc., you are limited to a few tens of calls, perhaps as little as five on a low-end box such as Raspberry Pi.

Many thanks for that informative reply Stewart. So is it good practice for better efficiency to enable Canreinvite on each extension? I have a SIP trunk connecting to my PRI media gateway for inbound and outbound calls, this doesnt have canreinvite, if I enable canreinvite on this, does that mean the calls will go from PRI to SIP user or SIP user to PRI directly, what will happen if I wanted on demand recording, since it isnt going through asterisk? If I wanted to use asterisk features, would I need to make sure canreinvite is off?

If so, maybe for better efficiency I can have internal calls from extensions to extensions using canreinvite and everything else without?

Asterisk will automatically inhibit re-invite when the Dial Command options include t, T, w, or W.

If you have one PRI, you probably don’t have to worry about re-invite anyhow, if transcoding is rarely or never done.

If you are still concerned, take a look at your CPU usage when you have 8 calls up. Extrapolating that to ~80% should give you a good idea of your expansion capacity.