This is the most reliable method for a "high quality" free unlock.
The most straightforward method is often contacting the device's current service provider. They can provide an unlock code if the device is fully paid for and meets their unlocking criteria.
Unlocking your ZTE ZXV10 B866V2 provides numerous benefits, including:
You'll need your device's IMEI number (dial *#06# to find it) and any other details requested by the unlocking service or software.