Are phone booths still around?

Yes, they are quite common. You do typically need a local phone card, which are widely available.

You can buy the phone cards in tobacco shops and newsstands which also are everywhere.

Buy a PIN card from a tobacco shop/newstand that is for the country you are in. They have directions for use on the back. There are cards for use in multiple countries, but they weren't as good of deal.

Although there are a lot of phone booths, they don't all work with every card. It's not uncommon for them to be partially or fully broken. If your card doesn't work. It could be the booth rather than you, try another one and look carefully for something that indicates it uses PIN cards.

I was in Germany in October, and I used pay phones on a number of occasions. I never had trouble finding one, particularly around railroad stations and bus stops. Post Offices often have pay phones, too. I had a prepaid phone card that I bought at the Post Office. However, if there were English language instructions in the phone booths, I never noticed. You may have to figure out the German.

I was just in London and Paris, and was surprised at how common the common phone booth was. On busy streets you would find one about every block or two.