User guide

VoIP System Telephones 133
Voice over IP (VoIP)
address sent with the registration and confirms the registration
request if the VoIP system telephone is listed in the menu
Telephony: Devices: VoIP Phones. The keep-alive time,
port number (8101) for telephony signalling and the value to
use for the TOS byte are also communicated in the registration
answer.
6. The VoIP system telephone creates a second TCP connection
using the signalling port number 8101 and sends a
registration.
7. Extra connections are created using the IP protocol RTP
(“Realtime Transport Protocol”) for call data when a call is
created. For calls between two VoIP system telephones, port
numbers above 8200 are used. For transmission to a Media
Gateway card, a port in the range 1024 – 1087 is used.
If you wish to operate a VoIP system telephone via a routed IP
connection (for example VPN or RAS) it may be necessary to con-
figure an external DHCP server accordingly. Please note the selec-
tion of the codec and keep-alive time for RAS connections. This
can be done by selecting the default profile RAS in the Teleph-
ony: Devices: VoIP Phones for the VoIP system telephone. The
operations software provided via TFTP must match the type of
device and communications system. You may also need to config-
ure BOOTP, DHCP and TFTP servers for the VoIP system tele-
phone.
Local Configuration
In addition to automatic configuration via BOOTP/DHCP, it is pos-
sible to manually configure a Forum IPhone 525 or a
Forum IPhone 535. This can make sense, for example, when you
wish to connect a VoIP system telephone at a distant location via
router. This local configuration is saved permanently in the non-
volatile memory of the VoIP system telephone. To change the
local configuration, use an additional programme, the Java-based
“IP Phone Configurator”.