Linux Journal: Writing an Alphanumeric Pager Server for Linux

For those thinking of setting up an alphanumeric paging
service or gateway, here is an explanation of the protocols and
methods involved.

“Alphanumeric pages–at least the type we will consider
here–are delivered via modem. To deliver a page, we connect to our
service provider, communicate with it through its specified
protocol, receive a confirmation that the page has been delivered,
then disconnect.”

“To send a message to someone, we need to know two things about
them: their pager service dial-up number and their PIN (personal
identification number). Alphanumeric pager owners should be able to
contact their pager service provider and get this information with
little trouble.”