How do parents get their children to check in when they are out with friends?

[TheEngineer]

Hi, I'm looking to see what way or how parents check their kids have arrived at their destination safely when they are out? I remember as a teenager getting my first mobile finding it embarrassing having to phone home to say I had arrived at parties etc etc
I guess a text would be fine but even then I feel I want to show I trust the kid and find that's too much as well.

Just curious as to why? Are you a parent or is this market research?

Why would a text be too much?
Kids are constantly texting, one to mum's not going to make a difference is it?

I call mine, otherwise I would wait forever for them to call/txt me..

Both, I was discussing the topic with friends and we discussed how differently our parents treated the issue and what we thought we would with our kids. I'm learning a new programming language as a hobby and thought it could make a tool that would be useful to people.

We used to have to give 2 rings on the house phone when we got to a friend's, then hang up so it didn't cost them anything