OnPage is excellent as an on-call doctor paging system; it replaces the need for our call center, lets us have our answer, and either take patient information or be patched immediately through. This gives us time to finish anything we may be doing that might be urgent without losing their information as it is written in the app or time to pull up the patient's chart before calling them back.
Not really a "downside": because it works so well, any details we haven't documented from our initial setup are probably lost. It's been almost four years since our initial configuration, and I can no longer easily navigate the OnPage site because I literally haven't logged in since the initial implementation.
Out of these, PagerDuty has been my favorite. OnPage is my second favorite so far. The two systems do the same thing. OnPage has a less painful punch in the wallet for the needed technology. The xMatters and ShoreTel Connect only redirect the call and trigger a single alert. Neither of these two products alerts a second time or escalates the ticket. OnPage and Pager Duty have escalation channels. OnPage has an easier scheduler to understand than Pager Duty, however.
Eliminated the concern that on-call personnel were not notified of an issue at all or on a timely basis
The reasonable cost, ease of use and reliability reassured management that any issues arising would be handled quickly
Users disliked carrying the bulky, unreliable and battery operated pagers. Today all users carry cell phones and can easily install and manage OnPage software