BT has conducted field trials that show it can deliver broadband download speeds of nearly 800Mbps using fiber and copper, a company announcement said yesterday.

The technology delivers data over fiber from the British telecom's facilities to neighborhoods while using copper for the final meters. Deployments of this sort are less expensive than fiber-to-the-home because they reuse existing copper lines used for telephone service and DSL.

"Previously it was thought such speeds would require a dedicated business line or a fibre optic cable to be laid all the way from a telephone exchange to a premises, a relatively expensive, disruptive and time-consuming process," BT said.

The field trials relied on G.fast, a new data transmission standard.

Speeds over copper degrade over distance, but BT said it was able to achieve 786Mbps download speeds over 19 meters and 696Mbps download speeds over 66 meters. Fiber and copper deployments can end up sending data over copper for much longer distances, further lowering speed, but BT said that 66 meters and below "encompasses around 80 percent of such connections." It's not clear whether the 80 percent figure refers to BT's existing network, the field trial area, or future deployment plans. We've asked the company to clarify.

BT said it "currently passes more than 20 million UK premises using a mix of Fibre to the Premises (FTTP) and Fibre to the Cabinet technology (FTTC)." G.fast requires Fiber To The Distribution Point (FTTdp), which brings fiber closer to homes than FTTC, BT said. This brings fiber to telephone poles or junction boxes, with copper carrying data the rest of the way.

BT's trials suggest that G.fast technology may not be far from real-world deployment. In the US, AT&T has extensively deployed fiber-to-the-node service that places fiber about 600 to 900 meters away from homes and tops out at 45Mbps. For faster speeds, AT&T is beginning deployments of fiber-to-the-home in limited areas. If G.fast proves promising, AT&T could bring fiber-like speeds to a greater number of customers at lower cost.

The 19 meter test that pushed 786Mbps downstream also achieved upstream speeds of 231Mbps for total bandwidth of more than a gigabit per second. For 66 meters of copper, it was 696Mbps downstream and 200Mbps upstream. BT said it can "tailor the allocation of the total 1Gbps speed according to a users’ needs," suggesting that a user could get greater upload speeds in exchange for reduced download speed.

G.fast could end up paving the way for multi-gigabit speeds. Alcatel-Lucent's Bell Labs in July said it sent 10Gbps over 30 meters of copper and 1Gbps over 70 meters using an extension of G.fast it calls XG-FAST.