If your device is locked to another network, this is not something that we would be able to assist you with unfortunately.
You would instead be required to contact the service provider (that the device is locked to) to ask if the device can be unlocked for use with another service provider. If your device cannot be unlocked, the only solution would be to use another device.
If you are being asked for a pin / passcode / password etc and you believe it may be for another reason however, please refer to the information found here: Pin / Password Lock Guide