Nokia E65 - Emergency Calls

Internet calls
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translation, not port mapping. This requires an external IP
address for each simultaneous connection. Broadband
routers often use this feature to allow a designated
computer to accept all external connections even when
the router itself uses the only available external IP
address.
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 E65 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.
Emergency calls
Your device attempts emergency calls primarily over
cellular networks. If an emergency call using cellular
networks is not successful, your device attempts an
emergency call through your Internet call provider. Due to
the established nature of cellular telephony, you should
use cellular networks for emergency calls, if possible. If
you have cellular network coverage available, make sure
that your cellular phone is switched on and ready to make
calls before you attempt an emergency call. The capability
for an emergency call using Internet telephony depends on
the availability of a WLAN network and your Internet call
provider's implementation of emergency call capabilities.
Contact your Internet call provider to check the Internet
telephony emergency call capability.