Make sure it asks for Network Unlock Code when you start it with another sim card.
IMEI Starting with 9 are NOT supported.
Network unlock code for ZTE
Make sure enough attempts are left to enter the unlock code.
Orders place on may take longer.
Unlock all ZTE Devices Including:
Zmax Pro
Blade Spark
Z812
ZTE Maven 3
Z850 Z
TE ZFive2
Maven
Blade
ZTE Avid Trio
Axon M
MF970
Maven 3
+ all other ZTE variants!