Registration from PUBLIC area via mobile phone-zoiper to my asterisk sip server?

Real sip ip phone could register to my Asterisk sip server. But this situation was in another place, public ip was static and i was connection via ethernet cable.
Now i am at home, my public IP address is not static but i know my public ip address. And now i downloaded zoiper to my mobile but it could not register to my asterisk server. What can be reason?
1-Firewall is disabled,
2-Router 5080 port is forwarded to 5060(in my router)
3-And Mobile phone-zoiper port was configured as 5080.(This phone reside is in another public IP)
4-Stun is configured as stun.l.google.com:19302

So why my phone can not register my asterisk server? When i change my mobile phone location as a same segment with my Asterisk Server(Asterisk server:10.0.0.100 and mobile ip:10.0.0.120) so mobile phone can register and can call any another zoiper phone. What is the problem when i change my mobile phone IP location as a global??