twilio

1. Register to https://www.twilio.com/
2. Create a project
3. Look for a „buy number” option
4. Pick the country and remember to tick the SMS option

Now you should have a number. To see SMSes, go to the # (Phone Numbers) option -> Active numbers
Click on the number and proceed to „Messages log”. Voila! Remember to change „Outcoming” to „Incoming”.
If you need to verify Google, use a UK number!

Method #2 (only numbers for USA)
Go to https://www.textnow.com/, register, enter a random area code. Voila, got a free number. Nothing to explain really.