If your phone is constantly ringing and there is no one on the line when you answer, this is caused by malicious scans on the public Internet and happens directly to your phone.
To stop these spam calls, you will need to adjust your firewall settings and ensure that network security is prioritised.
The Blueface firewall/router settings are the following:
1. We suggest setting the firewall traffic to facilitate ALL Traffic FROM and TO our IP range of 18.104.22.168/24 (Note that we do own the whole subnet).
2. If your firewall supports the SIP ALG feature, please make sure that it’s disabled.
3. UDP keep alive time out needs to be set to 200 seconds.
Please also check whether the port/s currently set on ‘5060’ can be changed to something else on your firewall.