For anyone not getting the cultural reference, it's due to a 40 year old pop song that used that phone number (as one belonging to a Jenny to be called "for a good time").

https://www.youtube.com/watch?v=6WTdTwcmxyo

In the overwhelming majority of US television and movies, onscreen phone numbers are of the form 555-xxxx to prevent clashes with those telecoms actually hand out. However, numbers of the form 867-xxxx are perfectly valid; and when Brown University made the mistake of handing out 867-5309 to an unfortunate dorm room around 1999 or so, those people were deluged with phone calls asking for Jenny.

That's a 415 area code number, and because Jenny has lived in Marin County the entire time (since 1981) she has never suffered an area code change like many in the Bay Area have over the years. ;)

UK does have official "media phone numbers" https://www.ofcom.org.uk/phones-telecoms-and-internet/inform... but none that are widely known and used I think.

I wonder if some stores flag it. I've used it a lot with success, but once in a Walgreens they asked me for the name on the loyalty account after I punched it in.

I think the parent comment was talking about a loyalty card discount at a supermarket that (I assume) only exists in the UK and Ireland.