ALG SIP on firewall, router, etc.

If you experience that when a call comes in your SIP device is not ringing this might be due that on your (ISP) router the SIP is enabled on the ALG level.

To solve this issue;-

1. Login to your router/firewall/etc.
2. Look for SIP (this is often under Network -> Advanced -> Firewall)
3. Disable SIP (see screenshot below)
4. Reboot your device

TIP: You can also do a web search in any search engine for "Disable SIP ALG" together with your router make and model it will likely show you how-to disable it.