[VOIPSEC] setting up trixbox - opening ports

[Robin Wood]

Hi
I'm new to voip and in the process of setting up my first server at
home. Going for Trixbox and going through a tutorial I got to this
point:

http://www.voip-info.org/wiki/view/Asterisk%40Home+Handbook+Wiki+Chapter+2#2531SettingupyourrouterfirewallsoAHcanco

Which basically says, add the following router rules:

Forward UDP Port 5060-5082 to 192.168.1.2
Forward UDP Port 10000 to 20000 to 192.168.1.2

Is this usual for a voip setup? From a security point of view this
seems like a bad thing.

Robin