I need to setup a paging system for a small school. This is not a problem, But they want a system that can be programmed to ring bells for starts and stops of class periods. Any ideas?

You can get a paging tone generator that's triggered by an external closure. You send the output through overhead paging. Then you can put any standard timer with dry closures on the "trigger" contacts. I believe Bogen makes them, and you can probably get them through Graybar.

I have a client who uses them to signal start/finish of lunchtime.

Viking makes a time controlled tone generator. Works simple, reliable. Have a couple in industrial settings for breaks and lunches.

Simple to program and change (which is important for a school setting)

I installed the viking unit. It gives you a choice of one gong. two gongs, or three gongs. You could wire up a second one to make other tones. Easy unit to program and has a nine volt battery for memory. A reasonable simple solution.

I've used the Viking CTG-1 Clock controlled Tone Generator. This unit has 128 time setting for a 24 hour period so the bells would have to ring the same time everyday. If they have a standard intercom panel this can be wired to a relay that puts system into all call mode. If you just need stright paging then this unit can feed into an aux input. Nice unit for the price. If you need more flexibility in the time schedule then I would use a YMP singal programmer from American Time & signal

look as well with the valcom paging systems
i have done tons in schools you can program audio groups con can also play wave files

I will check on the Viking unit with Graybar. Basically this is just an add on unit that sends a tone through a paging amplifier, correct? So we just install a paging unit and some speakers and add this too it, right?

I've never bought from them but the ones I have worked on at schools in the Dallas area were all Dukane. https://www.dukane.com

I also have used the Viking CTG-1, but instead of installing paging horns, I talked the customer into installing phones in every classroom and ran the output of the CTG-1 to the MOH port and turned BGM on for every phone that wanted to get the bells. Works great

Class connection by valcom.Have it in 5 schools as of now.Works ok,some quirks with the older ones.

i gotta push valcom cause i do tech support for them in ottawa canada helps with the bills

We've done a few schools that wanted a phone in each classroom. Toshiba has a program that runs on a computer hooked into a dedicated phone, very flexible schedules, different bell sounds, multiple zones. Office to room paging is done through the phones, bells and general paging also include the hallway speakers and outside horns. Easy to set up, no need for multiple systems, and no problems so far.

That is right if they don't have an intercom or pa already. If they do have a intercom system its not very hard to connect the Viking so it sends tone over the all-call channel or use a program channel if you want to zone the tones. Target Dist. sells this unit also.