The system seems to be installed correctly, but SIP phones cannot register. I checked the login, password, ports - everything looks fine. I suspect that the problem is in NAT or firewall, but I'm not sure. Does anyone have step-by-step instructions for testing SIP calls? I really need to understand where exactly the failure occurs. Any help or advice will be useful.

 

After successfully installing the system, I started having problems with SIP — the phones weren't registering, calls weren't going through, although the interface was working. I started checking ports, NAT settings, and the firewall. I spent a lot of time until I came across an article: https://host4geeks.com/blog/install-freepbx-linux/. It has an important section on setting up network interaction and SIP. It was from there that I learned which ports should be open and what settings need to be made in the configuration to make everything work. After applying these recommendations, the phones started registering, and the connection was successful. If your SIP is "silent", start with this article — it explains everything in great detail.

 

The final step in installing IP telephony is checking real calls via SIP. This will make sure that everything works: NAT, routing, device registration and audio transmission. Often at this stage, problems with ports, firewall or provider emerge. Therefore, it is important to test at least one call before starting operation. This will help to notice and eliminate critical errors in time.

 

Before starting the installation of IP telephony, you should update the system and install all the necessary dependencies. In most cases, errors occur due to the lack of necessary packages or conflicts between versions. Therefore, you should not skip this step. Use proven lists of dependencies and do not ignore the update - this will ensure that you get a stable installation without surprises.