It works also with closed ports

Hello :smile:

Curiously I have a question about… why IT DOES work :smiley:
I have an Asterisk server (based on Debian Linux) running in my office. It is connected to a standard Netgear router with some opened ports, but not 5060 or others that belong to the PBX.

Everything works well: I can place phone calls from the two HW phones we have at our desks and receive them from both the SIP provider I configured as inbound.

How can it work? And… what’s the point to open these ports in the router, if everything can work flawlessy without additional configurations?

Thank you in advance for your answers :smile:

That’s a question for the router vendor. I assume it has detected the register and automatically opened the port for incoming traffic.

This is a network consideration. I guess your asterisk server is behind a NAT done at your router level.

Afaik, this can be two things:

  • You have set ‘qualify = yes’ and your asterisk server will regularly send a SIP OPTION to your provider. This will keep the port 5060 open and forwarded to your asterisk server.
  • Maybe you have some kind of SIP inspection at your router level and it opens RTP ports on-the-fly