Although most Chinese cell phones are not tied to a network, or locked, in some cases a phone may be locked to a particular carrier's Subscriber Information Module (SIM) card. Chinese language versions of phones from major cell phone manufacturers can be unlocked in the same way as other langage versions of the phones. The exact procedure will vary somewhat, depending on the manufacturer and model. Specific unlock procedures are included with the unlock codes for your phone.
Acquire an unlock code for your cell phone. In some cases, the carrier in China may provide the number. If it won't, buy an unlock code from an online source.
Put a SIM card in the phone and turn it on.
Set the phone's language to English if you aren't able to read Chinese. If you can read Chinese, skip this step.
Follow the steps included with your phone's unlock code. The key sequences and procedures will vary, depending on your phone.
Turn off the phone and put a SIM from a different carrier in your phone once you have followed the procedure to enter the unlock code.
Power the phone on with the new SIM. It should recognise the network and register the phone with the number associated with the new SIM.
If you are in China, many cell phone shops can unlock your phone for a nominal fee.