LTP: if you're at a grocery store and don't have membership account, use the local area code and this number. It hasn't failed me in the 14 states I've tried it.
Back when you had to actually give the number to the cashier and they would read back the first name to confirm (or maybe it was if multiple accounts were tied to the same number, I'm not sure) I would always use this number with the local area code. Older cashiers would just put the number in and move on, below a certain age threshold they would say "Jenny?" and I would nod.
I do that at my stupid hair place: the clerk won't enqueue you without some random phone and a name to call when it's your turn. Then they wonder why there's a dozen people on that same number!
Or gas loyalty discounts, or really anywhere you need a throw away phone number. It just works. And if you have to deal with a human, especially one over 40 years old, you might get a wry smile, a wink, or even a chuckle.
I used it at the local Walgreens to get some kind of discount and there was $5 on the account but I needed to know the zip code used by the first person to claim it.