What a cool post, I used to be a telecom Tech and although I didnt repair cell phones but rather ease radios, Telephony and satellite equipment and the like,I do know what is in a phone and its not a lot if you look at the majo parts, the Circuit Board which is the brains of the phone
The Microphone and speaker, a keyboard on some but now thats mostly on the display, a battery and the antenna which you wont really notice its generally built into the chassis