What is it?
First of all we need to clarify what those are. The first one, i.e. MEID, is practically and ID of a phone and it needs to be said that each and every device has different MEID number, also known as serial number or ESN.
However, there are some devices without MEID. What now? Well, these devices have IMEI number, which practically has the same function as MEID. How to find these?
If this does not help, you then may need to check the settings for Android (Settings – About Phone – Status – scrolling until MEID/ICCID is shown) or iPhone (Settings – General – About – scrolling until MEID/ICCID are shown).
It can happen that these are placed under the batteries in the phone. To check, you would need to remove the back cover, the battery and then see the IMEI or HEX on the phones declaration.
On iPhones, MEID or IMEI numbers are often placed on the back cover of a phone, but the letters are small.