AT&T is expanding its Call Protect robocall blocking service to more customers.

AT&T Call Protect will be automatically added to millions of existing AT&T postpaid customers' accounts over the coming months, and new AT&T customers will come with the anti-robocalling service. AT&T says that Call Protect will also be added to lines where it's already automatically added suspected spam alerts, but not fraud blocking.

Customers who have Call Protect added to their account by AT&T will receive a text message when it's been added.

If you're already on AT&T and don't want to wait for Call Protect to be added to your account, you can enable it yourself right now. You can either download the AT&T Call Protect app for Android and iOS, or you can go into your account settings on myAT&T and turn it on there.

AT&T Call Protect can detect and block calls from fraudulent parties and identifies telemarketers and other suspected spam calls. The free service also includes a personal block list that lets you block calls by phone number.

If you pay $3.99 per month, Call Protect also gets you Enhanced Caller ID that'll identify unknown caller details, Reverse Number Lookup, and Custom Call Controls that'll let you choose call categories to accept, block, or send to voicemail.

Last month, the FCC ruled that U.S. carriers could begin blocking robocalls by default. That means that carriers can automatically enable robocall blocking services and let you opt-out if you don't want them. Some consumers may not know that their carrier offers robocall blocking services or may not know how to activate them, so the FCC decision helps to protect more people from robocalls and spam calls that can be annoying or worse.