NTT DoCoMo Tuesday unveiled its first handset to operate over its 3G cellular network while also providing VoIP calls over wireless Internet networks.

The N900iL will go on sale in Japan later this year and will be targeted at corporations for use by their employees, said Hitoshi Yasuda, a senior director of NTT DoCoMo's product business department, speaking at a Tokyo news conference.

The handset is based on a NEC cell phone, the N900i, which is currently being sold for NTT DoCoMo's 3G service. With the exception of the IP phone specific features, the phone is almost identical to the N900iL.

The addition of a wireless LAN chipset has added around 5 grams to the handset's weight and will also have an impact on the price. Yasuda expects the new phone to cost between ¥40,000 and ¥50,000 ($370 and $463) due to additional hardware and software development costs.

When used inside offices, the N900iL has the ability to act as an internal telephone for placing and receiving calls made over the company's private exchange. The handset can also be used as a conventional cellular phone whenever it is in range of a network signal.

In addition to simple voice calls, the telephone provides some extra features when used in a corporate environment, such as its ability to access and browse Web sites on the company's intranet through the built-in browser.

However, the phone will initially support only pages written in Compact HTML, which is the same markup language used by NTT DoCoMo's I-mode wireless Internet service.

The phone also provides an instant messaging service between users and features a buddy list-like function that can be used to quickly find out if certain people are inside or outside the office and, when in the office, whether they are in meetings, are available to take calls or busy.

Users won't be able to use the wireless IP phone features outside of the office network. NTT DoCoMo said it is considering adding support for its own M-Zone public hotspot service but didn't mention if it plans to offer support for other services.

By allowing the N900iL to work on any wireless hot spot, NTT DoCoMo could make the phone more useful for users who would be able to make free intra-company calls and send instant messages whenever they are within range of a hot spot. However, such a move could deprive NTT DoCoMo of some revenue.

The IDG News Service is a Network World affiliate.