With a prepaid annual subscription, they sent me a pager for FREE.

>builds simple, DIY kits for them

So I highly doubt this would be profitable for you.

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As far as the paging infrastructure is concerned, all the messages are mass-sent, in an un-encrypted analogue broadcast. EVERY device receives EVERY page, as long as within range. It is the pager itself which chooses to only display "your" message(s).

Your DIY hardware could lead you into some interesting discoveries of your local area's messaging/users.