Confused on RTP port negociation

Hi !

I’m littlely confused about the comprehension of RTP port negociation.

My provider use the range 10 000 to 60 000 for RTP.

Did I need to change RTP Port Ranges on FreePBX ?
This range, on FreePBX, it’s used only for negociation between users and Asterisk ? Also to negociate with our trunk provider ?

Thank’s for your help !

You need to let asterisk know to use this range under the Asterisk SIP settings and make sure that that range is port forwarded in your firewall to your PBX (if there is a firewall between your PBX and your trunk provider).

RTP ports aren’t “negotiated” exactly. Each side is independent, and does not need to use the same range. From a FreePBX perspective all you need to ensure is that traffic destined to your configured range in FreePBX is delivered to FreePBX.

The way it works in a general sense:
FreePBX to Provider (or Endpoint): Hey, I want to place a call to you. For audio you can send it to me at this IP address and this port.
Provider (or Endpoint) to FreePBX: Okay! If you want to send ME audio you can send it to this IP address and this port.

Similar happens for an incoming call, just with swapped roles.

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Thank’s for your example !

If I understand well, I can authorize 10-60000 on freePBX, for accept exchange with my provider, and 10-20000 on endpoint ? (supposing good configuration on firewall).

Would there be a real interest to reduce the range between freePBX and endpoint ?

You don’t “authorize” different ports or do it based on endpoints or providers. You don’t even need to change the configuration in FreePBX at all. You don’t need to touch the configured RTP ports. Only the firewall or NAT settings really matter.


I actually did not know this part.

thank you for your explanations !

Have a nice day :slight_smile:

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