Topic summary
Overlay plan
Extracted from the Wikipedia article Overlay complex.
Compromise
Most overlay plans introduced the inconvenience of mandatory ten-digit dialing in which the area code must always be included even for local calls. Ten-digit dialing is not a technically necessary requirement, and 917 was initially deployed without it, but a US Federal Communications Commission (FCC) mandate instituted it at the demand of major telephone companies, to whom an overlay is considered a disadvantage to competitors. In Canada, ten-digit dialing is also a requirement of the Canadian Radio-television and Telecommunications Commission in overlay area codes.