Smart Anti-Theft Smartphone Ecosystem with Offline Remote Access Using BLE and GSM

Tracking apps that run on a phone stop working once a thief switches the handset off or cuts its connection, so the owner loses both the device and any way of reaching it.This paper presents an anti-theft ecosystem in which recovery is handled by a separate companion tracker with a battery of its own, a dedicated SIM card and a built-in satellite receiver.The tracker combines an ESP32-class controller, a GPS receiver and a SIM800L GSM/GPRS modem.It sends its position to an online dashboard, replies to location requests received as text messages, issues an SOS alert carrying a map link when a button is held, and accepts calls from the owner.A temporary Wi-Fi page stores the device identity, API key, access point name, upload interval and emergency numbers in flash memory, so no secret is written into the program.A Bluetooth Low Energy layer that detects separation from the phone is specified as the planned extension.The prototype was exercised through its configuration portal and its text-message interface; the observed behaviour, including a location reply carrying six satellites and an SOS alert delivered with a map link, is reported.Weaknesses of the present firmware and the next development steps are also discussed.