I've run into this problem multiple times as well. I use their phone numbers to make a door code and despite telling guests the door code matches their phone number on Airbnb, I get someone at least twice a month that can't access the property because they aren't using the correct phone number. I've also had a guest get locked out of their account and didn't have an up to date phone number so I had no way to contact them. I don't understand why they don't verify phone number and email address before every booking just like you'd have to to book a hotel, airline ticket, or to do online shopping.