How to track my sim card?

A SIM card has no GPS and cannot be located on its own — only the handset it sits in can. So there are two separate jobs: kill the SIM so nobody runs up your bill, and locate the phone you left it in.

Step 1 — the SIM itself, through the carrier. Call your carrier's lost/stolen line (or use the app) and ask for the line to be suspended and a replacement SIM issued. Ask them to note the request time; that timestamp is what protects you from charges after the loss. Your carrier can see which cell tower the line last registered on, but they will only release that to law enforcement, not to you — a common myth is that a carrier will "track your SIM" for a customer, and they will not.

Step 2 — the handset, free. If it is an Android phone, Find My Device (google.com/android/find) shows last location, rings it, locks it or erases it. On iPhone, Find My does the same and can mark the device Lost, which locks Apple Pay. Both work as long as the phone is on and signed in.

Step 3 — blacklist the hardware. Report the IMEI to your carrier so it goes on the GSMA/CEIR blacklist; that stops the handset being reactivated on another network in most countries. The IMEI is on the box, the original receipt, or in Settings > About phone.

Step 4 — read what the line did. Your carrier's usage detail shows calls and SMS for the period, free, and that is often how people work out whether a lost phone was used.

Where our app helps afterwards. Once a replacement Android device is in hand, Ultimate Phone Spy — Android 4.0+, Windows and Mac, not iPhone — gives a persistent location history and geofence alerts at https://ultimatephonespy.com/location-tracker, which Find My Device does not retain. Plans run $69.90/month, $40/month quarterly, $16/month annual.

The line. Tracking a phone you own is fine; tracking a phone someone else carries, by number or by IMEI, is not — that is stalking conduct in most jurisdictions regardless of the app used.