Which allows 7D local dial across an area code boundary .
Which is uncommon today , requires central office code protection , locally if using toll alerting , across the entire area code otherwise , to avoid assignment of the same seven - digit number on both sides .
Allowing 7D local dial across an area code boundary , which is uncommon today , requires central office code protection , locally if using toll alerting , across the entire area code otherwise , to avoid assignment of the same seven - digit number on both sides .