We've all been there—an unfamiliar number appears on your caller ID and you wonder if it's a scammer offering to lower your bills by a zillion dollars or send you on a totally legit free vacation. T-Mobile subscribers are about to get a little more peace of mind when phone calls come in. The carrier is set to roll out network-level technology to identify and block scam calls, and there's no added cost for customers.

T-Mobile's new anti-scammer features come in two flavors. Scam ID will be enabled network-wide starting on April 5th. You don't need to install anything on your phone for this to work. When a call hits Tmo's network, it checks it against a known list of scammers to see if it's legit. This list is apparently kept up to date with "behavioral heuristics and intelligent scam pattern detection" on T-Mobile's network. If a scam is detected, your caller ID will say "Scam Likely."

If you don't want to see those calls at all, there's also the Scam Block feature. You can activate this feature starting April 5th with a dialer code. This automatically rejects calls identified as scams so your phone never rings. It's unclear how accurate T-Mobile's scanning is, though. It's possible legitimate calls will be blocked as well.

The anti-scammer features will be available to all postpaid lines, but it's rolling out to ONE accounts first. You can opt in and out manually using the following dialer codes (starting April 5th).