Don't think it's any better in terms of privacy, but it's a lot cheaper (or was, haven't looked into mobile plans in a long time), and it would condition me into not using it or relying on it often such that I could turn it all off and use it only when I need it out and about.

I'm not away enough or need critical alerts to need a beeper for example, so Id just leave it all at home I guess XD Shame they don't really make actually dump flip phones anymore.

PBX is a Private Branch Exchange (iirc). Just a server that routes a SIP trunk line(s) (voip) to individual devices like ATA's (desk phone) or mobile/desktop SIP apps for example. It can do smart things like voicemail, automated messaging, menus, transcribing, and a ton of other fun nerdy things.