[asterisk-users] solution for NAT issues?

[Ron]

Hi All,


I been having issues on my users behind NAT, even if i hard set a 
specific port on the phone, there are some network that NAT's it out to 
a different port, in turn, some time later the phone could not be 
reached by the server. i think because on the server, e.g. the user is 
still registered on port 49923 but when the request is sent to that port 
  the NAT router does not forward port 49923 to port of the IP phone, 
maybe nat mapping has expired or something.

I have tried STUN, still sometimes the phones just cannot be reached.
is there any other software to manage binding of ports on specific users 
so that the routers always keeps the port mapped to port of the ip phone .
TIA

Regards,
Ron