Under Settings menu tab, then left side menu SIP, there you will see Local SIP Port set to 5060. Change to something obscure like 9050 or any unused port.
This will fix cheap or low end router issues that mistakingly broadcast on the router WAN port where hackers and scanners are constantly looking for. Please note this does not make calls or provide access to the phone, it simply rings it with obscure caller IDs like all zeros, ones, etc...