Siemens Gigaset C470 IP User Manual page 124

Configuring telephone connections
If you enter 0 seconds, the registration will not be repeated periodically.
Area: Network
Please note:
If you have downloaded the general settings for your VoIP provider from the Siemens configuration
server (page 121), then some fields in this area will be preset with the data from the download (e.g.
the settings for the STUN server and outbound proxy).
If your phone is connected to a router with NAT (Network Address Translation) and/or a fire-
wall, you must make some settings in this area so that your phone can be reached from the
Internet (i.e. can be addressed).
Through NAT, the IP addresses of subscribers in the LAN are concealed behind the public IP
address of the router.
For incoming calls
If port forwarding is activated or a DMZ is set up for the phone on the router, no special
settings are required for incoming calls.
If this is not the case, an entry in the NAT routing table (in the router) is necessary in order
for the phone to be reached. This entry is created when the phone is registered with the
SIP service. In the interest of security, this entry is automatically deleted at certain intervals
(session timeout). The phone must therefore confirm its registration at certain intervals
(see NAT refresh time, page 124), so that the entry stays in the routing table.
For outgoing calls
The phone needs its public address in order to receive caller voice data.
There are two possibilities:
u
The phone requests the public address from a STUN server on the Internet (Simple
Transversal of UDP over NAT). STUN can only be used with asymmetric NATs and non-
blocking firewalls.
u
The phone does not direct the connection request to the SIP proxy but to an outbound
proxy on the Internet that supplies the data packets along with the public address.
The STUN server and outbound proxy are used alternately to work around the NAT/firewall
in the router.
STUN enabled
Click Yes if you want your phone to use STUN as soon as it is used on a router with asym-
metric NAT.
STUN server
Enter the (fully-qualified) DNS name or the IP address of the STUN server on the Inter-
net.
If you selected Yes
STUN port
Enter the number of the communication port on the STUN server. The default port is
3478.
Web configurator – configuring the telephone via a PC
in the STUN enabled field, you must enter a STUN server here.
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