Does an iphone 4 have an IMEI number?

Solution
https://support.apple.com/en-us/HT204073
Learn where to find your iOS device's serial number, International Mobile Equipment Identity (IMEI) number, Mobile Equipment Identifier (MEID), Cellular Data Number (CDN), and Integrated Circuit Card ID (ICCID) number.
https://support.apple.com/en-us/HT204073
Learn where to find your iOS device's serial number, International Mobile Equipment Identity (IMEI) number, Mobile Equipment Identifier (MEID), Cellular Data Number (CDN), and Integrated Circuit Card ID (ICCID) number.
 
Solution
Not all iPhone 4s have an IMEI number. Specifically, only the GSM-capable models have one. If your phone only shows an MEID, then chances are it's just a CMDA iPhone, and hence won't have/need an IMEI. (of course, that also means it can't connect to a GSM phone network...)