If you bought your Nokia 5140 on a contract from your cell-phone provider, chances are that it came "locked" to the network. It will not accept a SIM card from any other carrier unless you unlock it. Fortunately, the unlock codes for Nokia 5140 are available free online. There are unlock-code generators, which generate the code based on your handset's unique International Mobile Equipment Identity (IMEI) number. This is a 15-digit special code associated with your handset to identify it.
Instructions
1. Press "*#06#" on your Nokia 5140 keypad. As soon you as you enter this code, a 15-digit IMEI number will appear on your phone screen.
2. Go to a free Nokia-code-generator website like Unlock Nokia Free, Mobile Codez or Unlock4all (see Resources).
3. Enter your phone's IMEI number in the specified field and select your network carrier from the drop-down list.
4. Submit this information and wait for the website to generate the codes. On the next page you will see the unlock code for your Nokia cell phone.
5. Power off your Nokia phone, and replace the current SIM card with one from a different carrier. When you power it on again you will be prompted to enter the unlock code. Enter the unlock code exactly as the website shows it. You should then see the message "Network Lock Deactivated."
Tags: Nokia 5140, your Nokia, IMEI number, unlock code, Unlock Nokia, your handset, your Nokia 5140