here in this case there is no much thing todo you have to follow the same step to unlock it by Check the IMEI number of your MTN Fastlink. TO do this connect the MTN FAstlink modem on your computer, then click the profile to know the IMEI

then... you will need to get your UNLOCK CODE by clinking here www.a-zgsm.com/huwai.php
the nexst step is Type Your IMEI to the IMEI provided on the website and click calculate, you will immediate ly get the UNLOCK CODE
and then Change the sim in your MTN Fastlink Modem to another SIM other than MTN e.g. GLO, AIRTEL or ETISALA flow by Plug your MTN FASTlink MODEM to your computer, this time around it will prompt to type the UNLOCK code, then type the UNLOCK COde you get from the a-zgsm.com website. Please do not make a mistake because you have 10 chances.... then the work is don now you can enjoy and change any Sim of your choice .