In search field enter only digits without any other signs like spaces or "-" or "/". It might happen that the IMEI number will be longer than 15 signs. In such case you only enter the first 15 digits. All owners of a smarphone with an android or iOS software (iPhone or iPad) can check the IMEI number in the phone settings as well. Other devices like modems, which doesn't have a screen, need to check the sticker on the device to find the IMEI number.