Good morning, Suffolk County. Say hello to 10-digit phone dialing.

As of 12:01 a.m. Saturday, the area code 631 must be added to the regular seven digit number by those in Suffolk who are calling another Suffolk number.

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Callers dialing just seven digits can expect to hear a recording telling them to hang up and dial again, using the area code, said a spokesman from the state Public Service Commission.

As is the case now, callers within Suffolk will not have to dial a “1” because even with the added numbers, the call remains local.

All this, of course, is in preparation for the July 16 debut of the county’s second area code — 934 — which is being added because 631 “is running out of assignable telephone numbers,” and “a new area code is necessary,” stated a June 2014 report from the state Department of Public Service.

Existing phone numbers will remain the same, but anyone in the county who is requesting new residential, business or wireless service, an additional line or possibly a move of their service, could be assigned a number with the new 934 area code.

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As of that debut date, carriers could still have a ready supply of 631 numbers, so the introduction of the new code could take time to build up steam, said John Manning, senior director of the North American Numbering Plan Administration, which oversees telephone resources, including area codes.