Ah. I see you’ve encountered the telephone system of Whitby, Ontario. 
Originally, the town had numbers in the 668 exchange (central office code). That is, Whitby phone numbers were of the form (416) 668 XXXX, later (905) 668 XXXX after the split of area code 416 around 1994.
Sometime in the late seventies or early eighties, they added the 666 exchange. Someone probably told us of the 666 symbolism, but we considered it a kooky belief, laughed, and forgot about it.
There were always the weirdos on the east side of town who were telephonically served from Oshawa, and therefore had a 430 number, but in many ways they were more residents of Oshawa anyways. (Oshawa exchanges tended to be of the form 43x.)
After I left for university, Whitby acquired the 665 exchange.
Still later, Whitby acquired ten-digit dialing and an overlay area code, 289. We dropped the brackets and wrote the numbers as 905-XXX-XXXX or 289-XXX-XXXX.
Now Whitby has exchanges 220, 278, 483, 638, 893, and 989 in the 289 area code, plus exchanges 217, 430, 444, 493, 556, 665, 666, and 668 in the 905 area code.
It’s safew to say that any telephonic Satanicity has been greatly diluted.