Looks more of a toy, the Xun Chi 138 is probably the world's smallest mobile phone & if you wish to have the smallest mobile phone then nothing can beat this Xun Chi 138.
The phone measures only 2.64 inches in length & is less than two ounces in weight. A 260k color display, 1.3 Megapixel camera, Music playback function, GPRS, USB connectivity & handwriting recognition are some of its features. It is provided with a touchscreen as it is too small to have a numeric keypad. Small yet powerful.
World's Largest Cellphone
Maxi Handy (Maxi Mobile) is world's largest functioning mobile phone. "It measures 2.05 x 0.83 x 0.45 m (6.72 x 2.72 x 1.47 ft) and was installed at the Rotmain Centre, Bayreuth, Germany, on June 7, 2004 as part of the 'einfach mobil' infotour. The phone is made from wood, polyester and metal and features a colour TFT screen. It is fully functional and can send and receive SMS and MMS messages."