The Sony Ericsson K750, introduced in June 2005, was a high-end mobile phone, the successor to the now discontinued K700, and which was succeeded by the K800i in Q2 2006. Before official release, K750 was known by its codenameClara. There also was a T-Mobile exclusive version called D750i. Its hardware was similar to the K750i had T-Mobile branding with a light blue/white body and looked very similar to the Sony Ericsson W800.
Design
The K750i is a candybar style phone that weighs 99 grams, with its buttons that can be used with any finger. It has the 'dual-front' design common to most Sony Ericsson mobile phones since the T610, with the back of the mobile phone designed like a digital camera and intended to be held sideways to take photographs. The K750i is available in four colours, Blue, Oxidized Black, metallic red and Blasted Silver with a red version later released. The central joystick button is used for selecting options and navigating menus, with the "C" button as an 'undo' or 'delete' button, and the arrow-labelled button as a 'return' or 'back' button. The two buttons labelled by white horizontal lines, known as 'hotkeys' or 'soft keys' perform the function of making binary decisions, labelled on the phone's display. The button in between of these 'soft keys' acts as a shortcut key, which brings up a user-customisable shortcut menu when pressed. The on/off button is located on the top of the phone next to the IrDA port. There is one side key on the left of the phone; when pressed in standby mode, it opens either the RDSFM radio or the Media Player as selected by the user, allowing playback of WAV/MP3/AAC audio files, and 3GP/MPEG-4 video files. A press of this button in media player mode plays or pauses the selected media. The RDS FM radio has 20 user-configurable presets. The phone also features Sony's Mega Bass technology. The left-hand side of the phone also houses the Memory Stick PRO Duo slot for external solid state memory, which is protected by a flexible rubber cover. On the right-hand side of the phone there are three keys - two for controlling volume, skipping through tracks in the Media Player and zooming in and out when in camera mode. If the button is pressed when the headset isn't attached the phone displays a phone status screen showing profile, memory usage, battery level, and, on some mobile networks, phone number. The included handsfree headset is also required to listen to the radio since it functions as the antenna.
The phone has good all-round support for many versions of the MP3 file format, however support for WAV encoded files is not as extensive. AAC support is good, and the phone can only properly handle LC AAC. HE-AAC will play since HE-AAC is designed to be backwards compatible, however the SBR component will be ignored. The same is true with HE-AAC v2, only the normal LC component of the file will be played. The SBR and parametric stereo is ignored. Since HE-AAC v2 encodes the sound as a mono-aural track and the stereo separation is recreated through the PS data, HE-AAC v2 files played on a K750 actually play back in mono. The phone can also be used as a modem via Bluetooth, Infrared or USB. According to the Sony Ericsson website, the K750 has a talk time battery life of 9 hours and a standby time battery life of 600 hours.
Modding
Since K750i and W800i are essentially two phones with exactly same hardware specifications, soft modifications are available to convert a K750i to a W800i by using flashing software and the firmware files of the W800i model. Such modified phone will be able to use the Walkman feature which is available to W series phones only. Such phone can also use the flight mode option which allows the phone to work only as a media player while other functions, like cellphone radio system, are turned off. This option is useful when in places where mobile phone transmitters should be turned off. The Activity Menu will not be present which appears when the button between the left and right softkey is pressed. Instead the Walkman player appears when it is pressed. This modification will revoke any remaining warranty for the phone. Modding also called as flashing is done by software such as XS++ or Far Manager or SE tool.
Additionally the K750 shares its hardware with the lesser known D750, which has the interface of the K750, yet has a chassis similar to that of the W800.
