In typical use the person being paged makes direct contact with the sender once the page has been received. It's better than guaranteed delivery, in that the direct contact from the recipient closes the loop "completely", and guarantees that the message has not only been delivered but also read, understood and acted upon. The attempt to page continues until the contact has been made.

It's an old technology but it works. Large parts of the world are still installing new paging networks as their old ones reach end of life. Part of my day job is designing the equipment for such networks.