 If the added digit were 3, for example, numbers that already begin with a 3 would present a problem, probably resolved using either a "time-out" if the customer only dials seven digits, or a flash-cut to mandatory eight-digit dialing.Under this plan, the New Jersey telephone number 609-555-0175 could become 6909-3555-0175, although the added '3' in the middle block could theoretically be any digit.An advantage of expanding to 12 digits under this plan is that the area codes would be "consumed" at a much slower rate, as there would be ten times as many possible combinations in each area code.