The common components found on all phones are:
1. A battery, providing the power source for the phone functions.
2. An input mechanism to allow the user to interact with the phone. The most common input mechanism is a keypad, but touch screens are also found in smartphones.
3. Basic mobile phone services to allow users to make calls and send text messages.
4. All GSM phones use a SIM card to allow an account to be swapped among devices. Some CDMA devices also have a similar card called a R-UIM.
