Operation Manual

Tips and Tricks
Alice – 5 Tips and Tricks 23
5 Tips and Tricks
This chapter provides you with useful tips on using Alice and
on solving problems that may arise during operation.
5.1 Selection of the Video Device: Alice
Does not Display a Local Image
Alice offers the option of switching among different cameras
during an active connection. If no local image is displayed
after you start Alice, it may be that Alice is using another vid-
eo source installed on your computer. In this case, switch the
video source by pressing “Ctrl+T”.
5.2 Operation Behind a Firewall
If you would like to operate Alice behind a firewall, please
note the following:
Alice uses the video conference protocol H.323 for IP connec-
tions. In the firewall, the ports used for such connections
must be enabled for incoming and outgoing data. The TCP
port 1720 must be enabled for the control channel in accor-
dance with the H.323 standard. While connecting, additional
UDP ports from the range from 1024-65535 are determined
which are then used for video and audio transmission. In
some cases these ports must be taken into consideration in
the configuration of the firewall. For information about the
settings necessary for an H.323 connection, please contact
the manufacturer of your firewall.
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