HUAWEI Mate 9 Unlock

I suggest you to check with the MTN. Most likely your IMEI is blacklisted for some reason. 

As we know there is no online solution for your carrier.

If the phones are asking for the network unlocking code when you insert a SIM of a different carrier it means that you can buy a code to unlock them.

Once unlocked it is  possible to use the devices with any GSM carrier around the world. As Verizon is not a GSM carrier (it is CDMA) you'll not be able to use the devices with theri network. With T-Mobile, AT&T or any other GSM network everything will work just fine. 

Hello,

Unfortunately we cannot do more to help you. I suggest you to contact your local carrier to ask for assistance. Also, it is a good idea to ask assistance from a Samsung service centre.

Finally (after more than a month since the service is totally offline) we are performing some tests with a network unlocking solution for the devices running the T-Mobile Device Unlock app. We are in Beta now and it should take some additional days until we have a stable solution (or not :( ).

A more precise ETA is not available but I do not expect to take very long until the service will restart.