Can I lock android phone to one network? If can be unlocked if I have both lock and unlock code?
I want to lock my android phone to use only one network.
If you're talking about sim unlock, it is possible to re-lock it back to the network as was often the case with old nokia dumb-phones. However, I have not seen this in practice with most phones now-a-days. Usually, once it is unlocked from the network, any sim card can go in place and use it.
However, if you're talking about locking the boot-loader - then that's a different thing altogether, hence my comment above to ask for clarification. In this case, you can re-lock the boot-loader, depending on the manufacturer and the procedure used originally.