Net Calls Guide

Internet calls

	Define the Internet call settings using Set up internet telephone wizard
	Define the Internet call settings manually Define a SIP profile Define an Internet call profile Select a preferred Internet call profile
	Connect to the Internet call service
	Connect using a shortcut
	Make Internet calls
	Service settings
	Profile settings
	Other features
	Network Address Translation (NAT) NAT STUN
	Emergency calls

STUN

STUN (Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators (NATs)) is a network protocol allowing a client behind a NAT (or multiple NATs) to find out its public address, the type of NAT it is behind and the Internet side port associated by the NAT with a particular local port. This information is used to set up UDP communication between two hosts that are both behind NAT routers.

STUN is a client-server protocol. Nokia device 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. The response also allows the STUN client to determine what type of NAT is in use, as different types of NATs handle incoming UDP packets differently.

Protocols like SIP use UDP packets for the transfer of sound/video/text signaling traffic over the Internet. As both endpoints are often behind NAT, a connection cannot be set up in the traditional way. This is where STUN is useful.