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Configuring telephone connections
CE 450 IP R / IM-Ost english / A31008-M1817-R601_1-7619 / web_server.fm / 02.03.2007
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ion 2,
21
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The phone requests the public IP address from a STUN server on the Internet (Simple
Traversal of UDP over NAT). The phone's STUN server must be deactivated.
Set
STUN enabled
to
Yes
(see below).
STUN may not be enough, however, with your router's symmetric NAT. You may have to
forward an additional SIP and RTP port to the phone (Port Forwarding to all routers
involved, see page 75) and set a value outside the 5056 – 5071 range for the phone's
local SIP port (page 101).
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.
STUN server
Enter the (fully-qualified) DNS name or the IP address of the STUN server on the
Internet.
If you selected the
Yes
option in the
STUN enabled
field, you must enter a
STUN server
here.
STUN port
Enter the number of the communication port on the STUN server. The default port
is 3478.
STUN refresh time
Enter the time intervals at which the phone should repeat the registration with the
STUN server. The repeat is required so that the entry of the phone in the tables of the
STUN server is retained. The repeat will be carried out for all activated VoIP phone num-
bers.
Ask your VoIP provider for the
STUN refresh time
.
The default is 240 seconds.
If you enter 0 seconds, the registration will not be repeated periodically.
NAT refresh time
Specify the intervals at which you want the phone to update its entry in the NAT routing
table. Specify an interval in seconds that is a little smaller than the NAT session timeout.
As a rule you should not change the preconfigured value for the
NAT refresh time
.
Outbound proxy mode
Specify when the outbound proxy should be used.
Always
All signalling and voice data sent by the phone is sent to the outbound proxy.
Auto
Data sent by the phone is only sent to the outbound proxy when the phone is connected
to a router with symmetric NAT or blocking firewall. If the phone is behind an asymmet-
ric NAT, the STUN server is used.
If you have set
STUN enabled
=
No
or have not entered a STUN server, the outbound proxy
is always used.
Never
The outbound proxy is not used.
If you do not make an entry in the
Outbound proxy
field, the phone behaves independ-
ently of the selected mode, as with
Never
.
