[SOLVED] Active calls limit problem

Hey guys.

I am preparing a new asterisk server to move all our phones to.
I am facing a limit of the active calls and I dont know how to determine the reason.
I have 2 trunks , one is having 3 lines and the other 2, in the Outbound routes I have place them in order and start calling, I see that I am limited to 2 active calls, the 3rd one is “All circuits are busy now” So I check on the CLI :
CLI > sip show channels
I got 4 active dialogs from one of the Trunks. then I try to dial on a 3rd phone and I see there is an invite but no call.
I limit the first trunk to 1 channel and second left to 3(what it supports) and try again, I got the same result but now the first call is from the first trunk and the second is from the second trunk, So I assume that Trunks work great, the outbound rules use both of them , but somehow something is limiting me to only 2 active calls.
How I can find out the reason ?
P.S. I have also add option “maxcalls = 255” in asterisk.conf - no difference.

Version :
Asterisk 13.5.0

I think I have discover the problem. - Will test it out Monday on the spot.

I have test and play a lot with the machine, the RTP ports set on the gateway are different then the one I use by the settings, so I had in fact only 9 RTP ports… and on the gateway I have opened 3000 ports but on different numbers…
I just forgot to edit that part of the configuration.
So if I understand this correctly , 1 call require 4 ports ?

So active calls can be limited by :
Trunk channel limit, asterisk.conf maxcalls=255 , by SIP settings for port range.
Probably few more that I am not aware of right now