I have a phone, but, actually, I don’t use it as a phone.
In my phone book I have just 10-20 contacts, my family and friends.
With all other people, I'm texting on modern messengers, or voice call over them, because they are cheaper than voice calling over mobile operator.

I have only a few types of using my phone:
 * Texting or calling with someone over messengers.
 * Reading news, articles and mail.
 * Using special applications, like maps, taxi, weather, booking hotel.
 * Playing chess with competitors and solving chess puzzles.

I don’t use most of the features, like voice mail, speed dealing, hands-free, ring tones.
I do hate phone feature on my phone because I have a lot of voice advertisings and SMS spam.

But! If I’m on duty, I should be prepared for accepting calls.
On my job, we have a special robot with women’s voice, called Iron Lady. I have special contact with the picture of Margaret Thatcher.
Iron Lady calls to me if something is broken in our IT system and I’m on-call even late at night.

If I didn’t get a call from Iron Lady, she would try two times and then call to next on-call engineer. Next on-call engineer called “backup engineer”.
If you on duty and you want to go to the cinema or theatre, you should arrange with a backup engineer about this period of time.
If I haven’t been on-call, I would have better slept.
Also, if I haven’t been on-call, I would never have such experience of how our system works.

Our department about 20 people and we have weekly duties.
It’s like you have two weekly being on-call every 4 months.