Is it reasonable

[Ownyourchoices]

To expect a parent of a 14 year old to come get them if they get a call from another parent that they are drunk.

Yes, I would expect their parent to come and pick them up.

Depends whether that parent has had a drink themselves that evening or not. They might not be ok to drive.

They might also have their phone on silent overnight.

Depends really. I'd expect to have a phone conversation with them. I'd expect them to be there asap but e.g. if they're alone with younger DC asleep I don't think I'd expect them to come til morning.
Why are you in charge of the drunk 14 year old? Did they get the alcohol from you/your DC?

It's going to depend. Is the parent working a night shift? How drunk is the child? Is the parent able to drive eg. Have they had a drink? I would expect a conversation about it.

I would expect to be responsible for my teenager. Replace "drunk" with "broke leg"... phone on silent wouldn't be an excuse not to pick up phone then?

Not from my house - smuggled in from another source and downed at a party. My DC not drunk but part of group so came home with friend. Parents answered phone but want to have a fun night.

In this that case I think I'd be looking after the child but alerting social services, or possibly the police. That's not being unavailable to answer, that's abandonment of their responsibilities.