Any paging system will work. You need one with an amp that is large enough to power the required number of speakers for your particular application. I like Valcom myself- they have good audio, look nice, and can run on normal cat3 telco cable. Valcom also makes another line called Clarity that runs on 1 pair 18-20 gauge speaker wire. If you wanted something inexpensive with just a couple of horns for a small shop area, you could go with a Viking 2a-PA.