Verykool R16 - Manual (Page 19)

n
The SIM card has been locked since the wrong PIN code has been
inputted for three times. You must consult your network provider for
special PUK code with eight numbers to unlock the SIM card (The PUK
code may have been provided with your PIN code at the same time).
Warning:
The SIM card will be permanently locked if you input the wrong
PUK code for ten consecutive times and you must apply for a
new SIM card from your network provider.
14 Maintenance Guideline
Welcome to use R16. If there is a problem when you using the
phone, please contact with the vender or consult the local
maintenance center. If your mobile phone is in need of repair, you
can take your phone to local maintenance center, if there is no local
maintenance center, please pass your phone and the purchasing
invoice to the vendor.