Pelleg,
Bridged appearances are a lot different than hunt-groups. I just recently went through the exact same thing. MKU is right..if you setup a hunt group, you can set the "queue" field to "y", and it will queue the calls (probably as UCD-MIA)..
My issue was with ringing ALL Helpdesk phones (not just the available ones), and if nobody answered, it would go to voicemail. However, with that option also comes the ability to queue the calls if all agents in the hunt are busy..hence the inclusion of ACD functions such as "queueing" itself.
Lay out your exact needs for all conditions, or email me at JT@nserv.net
I spent a lot of time trial/error, and learned quite a bit about what's best for a small helpdesk queue. We were also using bridged appearances! BTW - our helpdesk is also 3 people with coverage to a 4th person if we're unavailable before going to voicemail...
Let me know directly if you get stuck, and want more detailed help.
Good Luck!
..i just did an extremely similar setup on a G3si.