As an agency we are constantly creating new Google accounts for clients. With the limits Google sets on how many accounts can be verified by one phone number, Google account verification can become a real chore. I know I have verified as many accounts as possible via my work phone, my cell phone, and my Google voice number. In the past, I have tried online methods for creating new phone numbers without much success. By far the best solution has been the Burner phone app.
This method isn’t free (well the first number is), but it is very inexpensive. Three credits ($1.99 or less depending on how many credits you buy at a time) will create a phone number for 14 days with 60 texts. With Burner, you can name phone numbers, so you know which number is used for what if you have multiple numbers at the same time.