Firewall/NAT

Does m0n0wall supports Full Cone NAT, or not?
I ask because it is very important for the proper working of SIP applications.
Thanks in advance.

If you mean 1:1 NAT, then yes.

Going by Wikipedia's definition.
"Once an internal address (iAddr:iPort) is mapped to an external address (eAddr:ePort), any packets from iAddr:iPort will be sent through eAddr:ePort.
Any external host can send packets to iAddr:iPort by sending packets to eAddr:ePort."

Full Cone NAT allows any external host to use the existing state table entry to access the internal host, kind of like a temporary port forward.

1:1 NAT doesn't require specifying any ports, they are all forwarded.

1:1 NAT is a mode of NAT that maps one internal address to one external address.
But my ISP gives me only one public IP address, my private network of over 10 machines and can not take more than one public IP address from the ISP.

If you only have one public IP address, 1:1 NAT is not appropriate for you.

Going by Wikipedia's definition.
"Once an internal address (iAddr:iPort) is mapped to an external address (eAddr:ePort), any packets from iAddr:iPort will be sent through eAddr:ePort.
Any external host can send packets to iAddr:iPort by sending packets to eAddr:ePort."

Full Cone NAT allows any external host to use the existing state table entry to access the internal host, kind of like a temporary port forward.

I sort of get your problem but why don't you just add a forwarding rule?

Never had any issues with my SIP phone behind m0n0wall (while using STUN).