These phones do not come with a pre-programmed phone number, and the merchant selling the phone would have no way to provide the phone numbers that were assigned to them. When you buy one of these phones, you call a phone number, tell them what area code you want the phone set up for, and they issue you a number. Unless you "refill" the phone with more minutes, you lose the phone number, and when you buy another throw-away phone, you call and get a new number.
I know this because my daughter's first couple of cell phones (at age 10-12) were prepaid becasue she had no real NEED for one, and did not use it often. I saw no point paying a lot more and committing to a 2 year contract to get a "regular" cell phone.
Now she has a real cell phone. Has had the same number for 7 years. And I couldn't tell you what it is to save my life. In my phone, it just says "L*****" and I pick that, and it calls her.
If these ladies immediately entered one another's numbers into their phones, and then assigned them names "Red", "Secret Squirrel", etc. and dialed all calls by name, they might not really KNOW what the assigned numbers were. An incoming call would show up on the screen as the associated name, the number would not appear.