You’ve just purchased a second-hand ZTE router, or perhaps you received a “free” unit from your Internet Service Provider (ISP). You plug it in, and a dreaded message appears: “SIM Lock – Network Restricted” or “Invalid SIM Card.”
The device asks for an "Unlock Code" when a non-native SIM is inserted.
Avoid anything named “ZTE Unlock Tool .exe” from random file hosts without SHA-256 checksums.
When you insert a different SIM card, the router enters a "Network Lock" state. Without an unlock code or tool, the router becomes a paperweight.
AT+ZIMEI? → 867xxxx Send IMEI to server → get unlock code AT+ZSNT=0,0,12345678 Response: OK
Assuming you have located a legitimate tool (e.g., or DC-Unlocker ), follow this protocol.
