It seems that in the US people have been more obsessed with spelling things with their phone numbers. A practice likely tied to a time when television advertisements and phone numbers needed to be remembered to be effective. I find that I ignore almost all phone calls from numbers I don't recognized due to the prevalence of telemarketers, so I can imagine how this sort of hierarchy of numbers might appeal to certain people.
There's only a couple numbers I actually remember... My grandmother's whose hasn't changed in 50+ years, my own google voice number, the one I use for everything, don't even know my actual cell phone number. I have contacts in my phone for that.
