Organization of school calls

In the lyceum with calls, everything is the same as in other schools: the guard presses a button, an electric bell rings, the human delay factor appears, and the sound is very old-fashioned, neither music nor voice announcements can be played.

But we would very much like all this to be automated. All technical means are there: a fire alarm system has been installed in the lyceum, to which a sufficient number of speakers are connected throughout the building. With this there is no problem, the input to the amplifier is a standard jack, you can connect whatever you want: a tape recorder, a computer, a PDA.

A week ago, we dug out an electronic “alarm clock”, specially designed for making calls on a schedule: there is a schedule for working days and weekends, a warning bell, in general, there are enough functions. But there is one “but” - the list is limited to 100 calls. Naturally, this is not enough. As a result, this Friday was with us a “weekend” from the music provided by the “alarm clock”.
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There is another problem: do not connect a simple microphone to the alarm clock, so that the voice announcements fall off.

So it was decided to look for an alternative for the PC. Connecting a computer to the system would not be difficult, and the use of the system will increase significantly. And why not school radio? :)

In general, I ask you to recommend me an alarm program, with an unlimited schedule, it is better if it is specialized for school calls, such as warning calls, playing music during breaks. Thank you in advance