@qianlianmin
Does your phone give you a message saying no SIM card detected?
If so do you have another phone you can put the SIM card in to see if you get the same message? This will determine if it's a device issue or a SIM card issue.
If it's a SIM card issue then it probably needs to be reprovisioned or if you just activated properly provisioned to your account so you would need to contact customer support as per the link in the above post.
If it does work in another in another phone then it's your phone and we will need a little more info to determine what the device issue might be?
