Lots of services demand your phone number after the fact now, hoping to use the sunk cost fallacy to extort it out of you when you're in a hurry.

Walmart recently deleted my phone number from my account for vague reasons but most likely because another account had the same number. That other account is my wife and the number is our VoIP line. I have no desire to interact with walmart through my cell phone so I didn't give it to them. So I used a google voice number, which is not my number, to get back in. Then they just bought my actual cell number from my credit card company and autopopulated the field. Jokes on me!