It's partly because of the low frequencies used that penetrated buildings better. My pager was 159Mhz. At those frequencies you have significantly less bandwid

It's partly because of the low frequencies used that penetrated buildings better. My pager was 159Mhz. At those frequencies you have significantly less bandwidth but pages were expensive so they weren't used for idle chitchat. That made it work with the low bandwidth available. And there really wasn't that much because with one-way pagers as used in Europe, all messages had to be sent out all over the entire country! Because the network had no way of knowing in which area a pager would be. So all you had was a 2400 bit/s stream for all nationwide users. That's why they made it so expensive.