Nokia is showing off a new iteration of a WiMax version of its Internet tablet at the CTIA conference in Las Vegas.

The newest and fifth version of the N810 tablet will become commercially available along with Xohm's official launch, scheduled for the second quarter. Xohm is the WiMax network that Sprint Nextel is building, with test networks already running in Chicago and the Baltimore-Washington, D.C., area. The new N810 will be available initially only in the U.S.

Previous iterations could connect to the Internet over Wi-Fi, with cellular connectivity notably absent from a device built by the number one cell-phone maker in the world. The tablet, which is slightly larger than a typical smartphone yet much smaller than a laptop, does let users connect to the Internet over cellular networks, but via a Bluetooth link to their cell phones. The new WiMax version will also have Wi-Fi, Nokia said.

The WiMax N810 will be available on Nokia's Web site and will also be sold by Xohm. Buyers can sign up for Xohm service over the air from the device if they buy it before subscribing for service.

The device is expected to be priced similarly to the other versions of the tablet. The most recent costs US$439 on Nokia's Web site.

WiMax offers faster speeds than the existing cellular networks. Nokia expects users will receive download rates of 2M bps to 4M bps, with bursts as fast as 10M bps. By contrast, Sprint's EV-DO (Evolution-Data Optimized) network, for example, offers average download speeds of as high as 1.4M bps.

While other cellular technologies like HSDPA (High Speed Downlink Packet Access) and EV-DO are not on Nokia's road map for the N810, the company will consider them for the future. "We're not excluding other technologies," said Mark Louison, president of Nokia in North America. The N810 is designed to be an open device that any developer can build applications for, and so it is well-suited to Xohm, which has said it intends to allow any device and any service to run on the network, Louison said.

While Nokia is eager for the N810 WiMax version to be used by other operators, Clearwire customers won't be able to use it, at least for now. That's because Clearwire isn't yet using the standard form of WiMax, 802.16e, supported by Nokia and Xohm.

The earliest version of the tablet, the N800, had only an on-screen keyboard, but subsequent versions feature a slide-out Qwerty keyboard. The tablets run on the maemo Linux-based OS2008 operating system and include a range of applications such as a Mozilla browser, Skype and Google Talk. It also includes GPS (Global Positioning Service).