WEST PALM BEACH, Fla. — Until recently, if you reported your phone missing, your carrier would cut off service to that device.

Whoever ended up with your phone, whether it was the thief or someone who purchased it from that person, could easily have the phone reactivated under a new account.

But on Oct. 31, AT&T, T-Mobile, Sprint and Verizon activated stolen phone databases, which enable customers to report and block stolen wireless devices.

“If your phone is lost or stolen, contact your carrier first thing,” said Amy Storey, spokeswoman for CTIA, the international association for the wireless communications industry.

By Nov. 30, 2013, the wireless carriers will be able to share data on stolen phones with each other.

The system works by keeping track of each phone’s unique identification number, similar to a VIN on a vehicle, Storey said.

In the past, SIM cards were blocked in an attempt to make the phone useless, but SIM cards are easy to replace.

Cell phone service providers are supposed to check the database before reactivating a phone. It’s expected the database will make a stolen phone a worthless piece of plastic instead of something that’s easy for a thief to sell.

If the original owner finds the phone, it can be reactivated if he or she provides proof of identity.

Here is some advice from CTIA and the FCC about how to protect yourself from smartphone theft:

• Lock it. As soon as you get a new smartphone, set a password to protect your device and change it on a regular basis. If you don’t know how to set a password for your Android, BlackBerry, iOS (Apple) or Windows smartphones, go to ctia.org/consumer for instructions.

• Make your lock screen display contact information, such as an email address or alternative phone number, so the phone may be returned to you if found. Avoid including sensitive information such as your home address.

• Write down the device’s make, model number, serial number and unique device identification number. This information can help police in identifying your phone.

• Add an app that will remotely track, lock and/or erase your smartphone. Some apps also will remotely trigger an alarm so people know that the phone is stolen or take a photo of the thief you can give to police. Find a list of apps at ctia.org/consumer_info.

• Save it. If you have photos, emails, contacts, videos or anything else that you want to make sure is available if your smartphone is lost or stolen, save it somewhere else such as a computer, USB drive or cloud service.

After your smartphone is lost or stolen

• Report it. If you know your smartphone is stolen, immediately notify your wireless provider so you can avoid incurring charges on the usage. If your device is lost, tell your provider to put a hold on your account so that if it ends up being stolen, you’ve prevented unauthorized usage. You may also report your smartphone stolen to the police.

• Erase it. If you have sensitive information, such as financial, health or work-related, or you believe your smartphone won’t be returned, it’s best to remotely erase it.