Nokia, the world's largest handset maker, announced today that it has started delivering its E61 business phone, the challenger of RIM's BlackBerry device, informs Reuters.

"First deliveries started late last week. It's gradually becoming available across the globe," said Pekka Isosomppi, spokesman for Nokia's Enterprise division.

Nokia E61 includes the same advanced business call features and IP-based telephony functions as the Nokia E60 and Nokia E70, it has a 16 million colors LCD display with 320 x 240 pixel resolution, a full attachment reader (documents, spreadsheets, presentations, PDF viewer and ZIP manager) and an editing function (document, spreadsheet and presentation).

In addition, a four-way joystick and the full QWERTY keyboard make the mobile e-mail easier, enabling users to send and receive e-mails while talking on the phone.

"The E70 model, with a 2 megapixel camera, is expected to start shipping later in May", Isosomppi added. The first E-series phone, the E60, went on sale in April.

Several software related issues delayed shipping of the three E-series phones, having a business target, and the prestigious three multimedia N-series handsets.