This was a while ago (about 15 I would say) and I managed the IT service desk for a large bank. We used pagers and the ticket system paged on various events. They were necessarily cryptic but the intention was to let the right people know when stuff was going on. The CTO would get paged if email went down, that kind of thing.
It was the dawn of the not-so-smart phone era and the executives got them along with people getting their own flip phones and such. Texting was starting to build. It was a great new world on the horizon. And the executives wanted us to step boldly into it.
Every few months I was asked why we didn't switch away from those old fashioned pagers and use this marvelous new technology. No more cryptic messages! No need to carry two devices! Stop being stuck in the past and move with the times!
I would politely listen to them and tell them (again) that SMS relied on email to get the messages to the towers. So just how I was I going to send a message that email was down if .. I used a system that depended on email to send messages?
It kept happening for years but that TAPI system just kept chugging along and the pagers worked everywhere, even in the more remote areas of the states when cell reception was 'stand on a hill and point your phone in the right direction' level.
It's nowhere near as important as medical professionals needing to be paged but it's an object lesson in using the right tool for the job. In this case the pager system is unlikely to get overloaded when there's a crisis or some other event where everyone is on their mobile phones. It might seem like it's an unnecessary expense but I'm guessing they looked at it like the executives at my bank did - a cost without knowing the value behind it.