This has nothing to do with mansards but rather phone number prefixes. When my family moved from Indianapolis to St. Louis in 1975, we lived in Brentwood and got a 962-XXXX phone number. I won't tell you the number because my mom still has the number at her house in Webster. My husband John also grew up in Glendale with a 962 number. His parents in Shrewsbury still have that number.
I suspect phone number fate brought John and I together. Our childhood numbers were only 2 digits different and we didn't live but a couple of miles from each other. I wonder: did I ever call him by accident in the 1970's? Did our paths cross at the Carl's Drive-in or the crappy Rock Hill McDonald's? Did we try on Dickies at the same time at Rudolph's? Perhaps we crossed paths at Goldies or Lauries.
Everyone's number in Webster/Brentwood/Rock Hill was 961, 962 and 968. There was no 918 or 963 prefix. Those are 'new' numbers (even though they've been around since the late 1980's) and the 961, 962 and 968 numbers are still preferred. 962, clearly, is the best.
As a kid and teen (and even still today), when someone tells me their phone number I only remember the 1, 2 or 8 and then the other 4 digits.
Here's my point. I live in south city now. I've swapped out the 962 for a 776. And now I have to think about 771, 772, etc. Same principle- remember the 1, 2 or 6. And now I'm a little snotty when someone has a 'new' prefix.
I was really mad to lose my 621-XXXX number when we moved from Lafayette Square to Soulard. Evidently we were just a little too far south to keep it. That was a great phone number.
We've had the 776 number since 2002 but credit collectors still call almost daily looking for some dude named James Thomas.