Response time
A conversation I earwigged, not being involved personally. But due to the nature of the issue I could not help but overhear.,
The on-call support person on a particular friday night was someone who "knew their rights" and worked to the letter of their job description.
At the time THE PHONE rang, they had just sat down to a romantic dinner at a local establishment. This was a time when any sort of mobile phone was quite a novelty, before the era of smartphones and laptops. It was not recorded whether that "romance" involved anyone else, but I digress.
It turned out that the support person knew that the conditions of being on call required them to respond within 45 minutes. So 40 minutes after the phone rang (and apparently rang several more times) they called to find out what was interrupting their carefully planned, to coincide with being on call, night out.
The details of the emergency were not part of the post-mortem, but downtime of the main server was said to be in the order of £5-figures per hour. What was apparent was the difference in interpretation of what "respond to a call" meant.
It was explained to the support person that responding meant presenting themselves in body and mind at the premises to perform whatever was necessary to resolve the problem. This explanation was made loudly and in words that left no room for misunderstanding. And that when the on call phone rang, they were pretty damn well expected to answer it instantly.
Production issues of this nature were quite rare, so the depth of the support person's understanding was never tested.