Internet calls Your Nokia E61i supports voice calls over the Internet (Internet calls). With the Internet call service (network service), you can make and receive calls over the Internet. Internet calls can be made from places that have a broadband connection and WLAN access, e.g. homes, hotspots at airports, and cafes.
Network Address Translation (NAT) Nokia E61i supports STUN (Simple Traversal of UDP Through NATs) servers for NAT (Network Address Translation) traversal, for networks where you do not have a public IP address. Even with STUN servers in use it is possible that the connection will not work, as some types of NATs still block the traffic.
UDP communication between two hosts that are both behind NAT routers. STUN is a client-server protocol. Nokia E61i includes a STUN client which will send a request to a STUN server. The server then reports back to the STUN client the public IP address of the NAT router, and the port opened by the NAT to allow incoming traffic back in to the network.