3CX and MicroSIP port translation Requirements

[VUSALDADASHOV]

After registering the SIP Trunk, when it turned green, I tried to call this number from my mobile phone, but the call never went through.

I realized that I had to disable SIP ALG on the firewall, plus I had to transfer port 5060 to 3x for the SIP provider.

But before I do that, I did a little test I downloaded the MicroSIP program to my computer, registered a SIP trunk there and could make and receive calls. Moreover, I spoke for 8 minutes and did not experience any difficulties.

And when it came to 3CX (I think it’s not a matter of 3CX; in principle, any other SIP server requires this), it’s necessary to translate udp and tcp port 5060 to the SIP server. Otherwise, the call simply does not go through or the call goes through but is interrupted. And I do understand that this is only necessary for the SIP provider.

I’m just wondering why in the first case port translation was not required, but in the second case there’s no way without it?

 

[Alphabetic]

Does your 3CX pass the firewall test?

 

[VUSALDADASHOV]

After registering the SIP Trunk, when it turned green, I tried to call this number from my mobile phone, but the call never went through.

I realized that I had to disable SIP ALG on the firewall, plus I had to transfer port 5060 to 3x for the SIP provider.

But before I do that, I did a little test I downloaded the MicroSIP program to my computer, registered a SIP trunk there and could make and receive calls. Moreover, I spoke for 8 minutes and did not experience any difficulties.

And when it came to 3CX (I think it’s not a matter of 3CX; in principle, any other SIP server requires this), it’s necessary to translate udp and tcp port 5060 to the SIP server. Otherwise, the call simply does not go through or the call goes through but is interrupted. And I do understand that this is only necessary for the SIP provider.

I’m just wondering why in the first case port translation was not required, but in the second case there’s no way without it?

I forgot to add that I passed this project, and in principle I did not have any difficulties.

 

[VUSALDADASHOV]

I forgot to add that I passed this project, and in principle I did not have any difficulties.

Does your 3CX pass the firewall test?

to be honest, I didnt event check this.
I knew there were no port translation at all, so all test would fail certainly

 

[SweetAction]

After registering the SIP Trunk, when it turned green, I tried to call this number from my mobile phone, but the call never went through.

I realized that I had to disable SIP ALG on the firewall, plus I had to transfer port 5060 to 3x for the SIP provider.

But before I do that, I did a little test I downloaded the MicroSIP program to my computer, registered a SIP trunk there and could make and receive calls. Moreover, I spoke for 8 minutes and did not experience any difficulties.

And when it came to 3CX (I think it’s not a matter of 3CX; in principle, any other SIP server requires this), it’s necessary to translate udp and tcp port 5060 to the SIP server. Otherwise, the call simply does not go through or the call goes through but is interrupted. And I do understand that this is only necessary for the SIP provider.

I’m just wondering why in the first case port translation was not required, but in the second case there’s no way without it?

So when you register against most SIP Trunks with any program, you are making an outbound connection to the provider. Your firewall may map 5060 to some random port (SIP ALG) and create a state between the SIP server and the provider. The provider gets the packet like "IP1.2.2.3 port 65478 is registered" and when it sends back traffic to that IP and Port, as long as the state is still open on the firewall, the firewall sends it back to the SIP server.

When that state closes, without a port forward, the firewall drops the traffic.
With SIP ALG, the provider sends it back to that random port contained in the register request, and that causes the port forward to be invalid.

One way to get around this is using keep-alives, but not all systems can do this nor can all systems handle this. Much of how well this trick works is dependent on your firewall, your SIP server, and your provider.