1. Do not use 5060 as your default SIP port number of the Asterisk server as there are many VoIP hackers in the world. Change any port number that you want, for instance 10003.
2. If you use ordinary router (not Mikrotik RouterOS), you may just do the port forwarding SIP port number (UDP) and RTP port number (UDP) as defined in your Asterisk server.
3. If you are using Mikrotik RouterOS, you need to add a rule to accept the packets from ComNet IP address 202.0.179.3 in the FORWARD chain of Mikrotik RouterOS firewall (ip/firewall/filter).