John's Phone. Business - Black. The World's Simplest Mobile Phone Works Worldwide - The world's most simple unlocked mobile phone has built-in quad band. A quad band mobile phone allows you to use the 4 types of GSM networks: 850, 900, 1800 & 1900 Mhz. This means you can make and receive calls anywhere in the world (except Japan & South Korea). John's phone is compatible with Pre-paid Pay As You Go SIM cards, SIM only contracts, National & International SIM cards. NOTE: Works on all UK networks except for Three (3 network) John's phone battery is energy-efficient (1200 mAh), as it does not contain any energy-consuming features. The talk time of John's Phone is approx 6 hours and the standby time is more than three weeks. John's Phone has a single ringtone with three volume settings: loud, normal and silent. You can adjust the volume using the button on the left side of the Phone. The vibrate function works for all settings. You can save 10 speed-dial numbers to your John's Phone: one under each number key. In the box are the following: John's Phone, Instruction Manual, Headset, Charging Unit + USB Cable plus a unique accessory - an Address Book & Pen NOTE: The supplied charging unit is a European 2 pin plug but comes with a free USA adaptor. Alternatively you can use the supplied USB cable & connect to your computer Unlocked cell phones are compatible with GSM carriers but are not compatible with CDMA Carriers.