The New York State Public Service Commission has announced that the North American Numbering Plan Administrator (NANPA) has assigned a new 680 area code for the area currently under 315, which includes St. Lawrence County.

Local telephone companies have been directed to activate the new 680 area code by the first quarter of 2017, the PSC said.

The new area code will be overlaid, or superimposed, on the existing 315 calling area, which will result in more than one area code serving the same calling area.

All existing telephone users in the region will retain their entire current phone numbers, including the 315 area code.

Once the new code is activated, new telephone numbers will be assigned to either the 315 or the new 680 area code.

In addition, telephone calls to any number within the region, even with the same area code, would not be completed without first dialing the 3-digit area code, and then the 7-digit number (10-digit dialing).

To implement the new overlay area code, there will be a seven-month period for network preparation, followed by an 11-month permissive dialing period that allows both 7-digit and 10-digit (area code plus 7-digit number) dialing to work.

After this period, 10-digit dialing will be mandatory. Misdialed calls will trigger a message directing the caller to dial 10 digits.

This schedule should permit the activation of the 680 area code in early 2017.

During the implementation timeframe, the PSC will conduct outreach to ensure that customers are aware of the area code change and its ramifications.

Earlier this year, NANPA informed the PSC that the 315 area code was projected to have a shortage of numbers by no later than the first quarter of 2017.

To provide area code relief as required by federal law, the PSC examined “overlay” and “geographic split” options, and determined that an overlay code was the best option.

“An overlay code is easier to implement, less expensive, easier for customers to adapt to, and fairer to all customers,” a statement from the PSC says.