Nokia has launched the E55, its slimmest smartphone yet, at Mobile World Congress.

The E-series phones have traditionally been seen as enterprise devices, but the E now stands for efficiency, said Nokia: they are all about doing more with less - more work with less phone, less money and less time, said Kai Öistämö, executive vice president at Nokia.

The secret to the E55's thinness is in its keys, he said. It's Nokia's first compact Qwerty device, he said, and has half as many keys as the company's previous thinnest smartphone, the E71. It will also have the longest battery life of any of Nokia's smartphones, with up to a month of standby time, he said.

The Nokia E55 is the company's slimest smartphone to date

The E55 runs Nokia's Symbian S60 software and has an Assisted Global Positioning System (AGPS) receiver, Bluetooth, Wi-Fi, a 2.4in 320x240 pixel screen and a 3.2Mp camera. It's not all about work: there's also a 3.5mm headphone socket for listening to the digital music player or the built-in FM radio and support for Nokia's N-Gage game platform. The phone will ship in the second quarter of 2009 for around €265 (£237) before tax and operator subsidies.

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Nokia also unveiled the E75, the successor to the 9000 series Communicators. It has a Qwerty keyboard that slides out from behind the 2.4in 320x240 pixel display, and a regular dialling keypad just below the display. Like the E55 it has a 3.2Mp camera, AGPS, Bluetooth, Wi-Fi, and a FM radio and music player, but the key feature is its support for email. It simplifies connection to Lotus Notes, Microsoft Exchange, POP3 and IMAP email services, or webmail services such as Gmail, said Öistämö.

"There's no need for middleware and no need for the BlackBerry tax," he said, referring to the additional BlackBerry Enterprise Server licence fee that businesses must pay if they want employees to access corporate mail via BlackBerry handsets.

The E75 will ship in March for €375 (£335) before subsidies and taxes.

It will be the first device to provide access to corporate email through the Nokia Messaging service at no extra cost. Nokia has wider ambitions for this service: it plans to make it available across all E-series models and 40 other devices, extending push email to over 100 million Nokia users.

"We are now spreading it further than just smartphones," he said.

The E55 and E75 will work with other services from Nokia available through its Ovi online portal, including an online store that Nokia also announced. The store will help users find useful applications by recommending those popular with their friends, relevant to the city they are in, and that are sure to work with their phone.

See also: Nokia to slash mobile phone production