Washington ? Starting today, if you have Caller ID you’ll know when a telemarketer is trying to reach you.

That’s when Federal Trade Commission regulations kick in requiring telemarketing firms to identify themselves.

Such calls had shown up on Caller ID as “out of area.” Now the name displayed by Caller ID must either be the company trying to make a sale or the firm making the call. The display also must include a phone number that consumers can call during regular business hours and ask that the company no longer call them.

The change is part of the rules that set up the do-not-call registry, which consumers can use to block certain telemarketers from calling. Telemarketing companies were given additional time to install the technology needed to display their names and numbers. Some places still don’t have Caller ID technology, and firms in those areas do not have to comply.

The do-not-call registry, which began in October, now contains 56.3 million phone numbers.