In most countries outside North America, if you don't pay the phone bill you can still receive texts and calls. You just can't make calls, send texts or use internet.

The same applies to prepaid cards - if the balance hits zero, you can only do incoming calls and texts.

Obviously, the provider will still send debt collectors if you were on some fixed price per month plan, and those debt collectors will still try to collect moneys for the months the service didn't allow outgoing calls... I always thought it odd that a company was allowed by law to collect money for a service they didn't provide.

Yes, if I'm on a prepaid plan? If I didn't top up, my phone would still have an active SIM and phone number. I would still be able to receive calls and texts.

In Germany at least you (can) buy a prepaid sim card and activate it. That gives you a phone number and you usually get the price you paid for the sim card added to your account balance. From then on you don't have to pay anything to keep using that phone number to receive calls/SMS. Calling/sending SMS costs are coming of your balance. You can buy packages (usually good for 4 weeks) with e.g. 300MB data volume or unlimited calls.

There's also the model where you pay a monthly subscription and receive a new device every few years or have some other benefits.