Network bandwidth problem

[Laszlo Zsolt Nagy]

  Hi All!

I have a little problem here. I'm going to have two employees here who 
are making calls with skype.
There is a router (FreeBSD 5.3) and a NAT-ed network. Internet is 
accessed via ppp (DSL line).
When the network is loaded heavily, skype is breaking up. Is there any 
way to configure my router
to prioritize packets for skype users? The speed of incoming traffic 
cannot be limited efficiently,
am I wrong? What I probably need is to limit bandwidth and/or set packet 
priority by port number.
I'm not sure about the protcocol of Skype in this case because we would 
like to use it to make calls
to regular phone numbers. I'm not really new to ipfw but what I have now 
is a configuration that
was changed from an example. Any URL pointing to the right place will be 
appreciated.

Best,

   Laci