Mess Call Up System Design/Finding

[Shelster]

Hi all

Need a little help.  Currently in work, we have a mess where only people of a certain rank are allowed in.  If somebody wants to see if someone is in there, currently we use the old fashioned way of klnocking on the door and waiting for an answer.  This does work, but for us in the mess, is a bit of a bind having to get up all the tnme and answer the door.

We are lopoking for a system that can be fitted that achieveas the following.

1 - The person at the door dials in a number on either thumb wheels or a keypad and presses a call button.
2 - This number is displayed on either a double 7 segment LED display, LED notice board (ie system recognises number and displays name inside mess) or a LCD display doing the same.
3 - If the called person is in, then a positive responce is returned and a green light under a 'Wait' sign lights.  If they are out, then a negative response is sent and a light  under a 'Out' sign lights.  This 'Out' will also light no response is received after a set time. (these lamps could be replaced by a LCD message)

Does anyone have any designs for something like this already, or know of such a system?

Understand this is going to be a micro-controller based system, but would iddeally like it interfacable with a PC,. so names can be changed as people come and go.

Many thnaks for taking the time to read this and thanks in advance for any help/advice received

Paul