What does "pager" means in the Site Reliability Engineering jargon?

Question

I'm just learning about SRE and I find that term frequently. It seems to be related somehow to be on call, but not sure how.

Answer 1

Literally it is one of these:

It's a pager. It's an analogue device that was originally used to let you know someone was trying to reach you, and later supported basic text messages. It existed in the dark ages before mobile phones, and is still used sometimes in some fields.

Practically it means you're the contact person in case something goes wrong. You're basically on standby. These days it will be a phone call telling you to drop into Hangouts or Slack or something, or to go into your workplace since something went wrong.. It does mean however that you better answer your phone no matter what time it is.

Some places probably still use pagers, but the analogue networks that supported them are getting shut down as time goes on.

Now, get off my lawn.

Answer 2

It's a wireless device used for receiving messages. When you get a message, the pager would beep or vibrate to let you know. Typically, a pager could only receive messages, though some allowed the user to actively respond.

Being on "pager duty" is basically the same as being "on call": you're not actually working but you need to be ready to take on work at a moment's notice.

My mother had one in the 1990s for her job but got rid of it shortly after she got her first cell phone. Though no longer widely used, there are a few applications, such as emergency police, fire, and medical services, that continue to use pagers.