Nokia E52/E55
The Nokia E52 and Nokia E55 are smartphones from Nokia's business-oriented Eseries range. They run Symbian OS v9.3 (S60 3rd Edition FP1). The E55 was announced on 16 February 2009, whilst the E52 was announced later on 6 May 2009. They are both physically and functionally identical, except that the E55 has a 'half-QWERTY' keyboard, similar to the SureType keyboard on BlackBerry Pearl, whereas the E52 revision has a traditional T9 keypad. They are available in Black, Black Aluminum, Metal Grey aluminium, White Aluminium and Gold. They came with a 1GB MicroSD memory  card, but it supports MicroSD cards with up to 32GB memory. It also has 60 MB free user memory. The E52 is the successor to Nokia's successful E51 model. Latest firmware version is v091.004 released on June 2, 2012. The E52 and E55 were, at 9.9 mm thickness, very slim for its time, and feature mostly metallic bodies. Nokia called the E55 the world's thinnest smartphone (it was just 0.1 mm thinner than Nokia E71). The E55 model has a unique 'compact' QWERTY keyboard featuring two letters in the QWERTY order on a single key. Battery life . It has been observed that the 5.5 Watt-Hour, 1500 mAh, 3.7 V battery can easily last 27 days of practical use. This is considerably higher than other phones in its class made by Nokia and other manufacturers. If WiFi, Bluetooth are used and built-in VOIP client is active, the battery will last about 24 hours.