Comment by pdkl95

> cell network

Pagers do not use the cellular network. (some cellular networks do provide paging-style services, but that is a later development that is unrelated to traditional pagers)

> A 'receive only' pager still needs to announce itself

A traditional pager doesn't have a radio transmitter.

> they're not just multicast

The message is broadcast region-wide using very low-bandwidth protocols[1]. A pager will generally only work inside the region it is registered with. To compensate for the lack of ACKs, the message is usually repeated several times; it will missed if the pager is off for all of the transmissions.

[1] https://en.wikipedia.org/wiki/FLEX_%28protocol%29