Nowadays people mostly use cell (cellular) phones (US) or mobiles (UK). But you also use office phones, public phones and home phones. To make a call by a public phone you need coins or a card or tokens and there is a slot for them. When you pick up the receiver you can hear signals and these may differ from country to country.

Different countries have different country codes, e.g. 372 for Estonia.

You should give your number in the following form: +372 7373 998. You also must know the area code but sometimes it is included in the number already.