Starting today, all Suffolk callers will need to dial the area code to call any number, even other Suffolk numbers with the same area code.
The change comes ahead of July's rollout of the new 934 area code, which will be given to all new Suffolk numbers.
News 12 spoke to a number of Suffolk residents who were caught off guard by the new dialing details.
"When people say 'what's your phone number', they say 631, I don't even bother writing it down, now I'm going to have to write it down," says Kere Kowalsky.
Michelle Ardito, of Lindenhurst, says she'll never have a 934 number and that she might even ditch her old 631 soon.
"Too many people on Long Island though, I think it's time to get out of here," said Ardito.