If you're worried about security, it wouldn't matter that you use pagers. You just wouldn't be transmitting any data that made sense to anyone. Whether through obscurity (i.e. "the guest has landed", or codebook numbers) or encryption, it wouldn't be any use to an outsider with hostile intent.
That we're still using pagers, I find amusing, but it's more about WHAT you send, not how you send it. The number of people I meet that think that email is "confidential"... shocking news when their email server will happily send in plaintext still.
We don't need technology updates or end-to-end encryption (which, actually, makes us more lazy and slack with the data we spew). We just need simple data management. Don't send anything that you wouldn't want others to know.