First of all, you can find the necessary information in the Settings app on your device.

Take the following steps for that:

  1. Go to Settings > General.
  2. Tap About.
  3. Look for the serial number. Just scroll down to find the IMEI/MEID, and ICCID.

Furthermore, the serial number of the device is also indicated on the original product receipt or invoice.

Just as easy as it is :)