One of the topics creating a buzz at the recent SatCon satellite conference in New York was the imminent launch of an Inmarsat satellite that will deliver broadband connections to magazine-sized portable transceivers.

The six-tonne Atlantic Ocean Region I-4 satellite was scheduled to lift off last Friday. Once tested, it will serve as the platform for Inmarsat's BGAN (Broadband Global Area Network) service, enabling small, battery-powered portable terminals to support 492K bit/sec data rates and separate voice traffic.

The Atlantic Ocean satellite will serve the Americas when the service is turned on in April, complementing an identical bird parked over the Indian Ocean that will service Europe, Africa and most of the Far East, when it comes online on 16 November (if all goes as planned, Inmarsat will launch a third satellite over the Pacific in late 2006.)

Use of high-powered, focused spot beams, along with a 25 times improvement in sensitivity, is what makes use of small, low-powered terminals possible.

A handful of companies are building the terminals, including Hughes, Nera and Thrane & Thrane. Data rates vary by terminal type, with a maximum of 492K bit/sec shared, meaning data rates drop as more users log on (if hotspots develop, Inmarsat says it can aim more beams at a given area). Billing is for megabytes transmitted. Customers will be able to reserve data channels of 32K, 64K, 128K or 256K bit/sec, with billing based on session duration.

Voice, which is handled on a separate 3.1KHz channel, is said to be almost toll quality. Both dial-in and dial-out are supported, as are a host of common features, such as caller ID, call forwarding and voicemail.

Thrane & Thrane's new US$2,850 (£1,615) Explorer 500 is 8.5in square, 2in thick and weighs less than 3 pounds. It has an RJ-11 telephone port, an RJ-45 LAN port and can be powered by its internal battery for as long as 1.5 hours when the unit is transmitting full time at 144K bit/sec. The maximum shared data rate is 464K bit/sec down and 448K bit/sec up, with reserved speeds of 32K, 64K or 128K bit/sec.

Transmission costs are just emerging, but are said to range from about $3.50 (£2) to $7.50 (£4) per megabyte.

While that seems expensive, some buyers at SatCon were eager to test BGAN. One said privately that he would consider buying 5,000 terminals if they would enable his field personnel to service customers directly from their homes, negating the need for local offices.