The headaches involved with Project Pronto, which was to extend digital subscriber line service to remote terminals, led SBC to turn its attention to moving passive optical nets (PONs) deeper into residential and business neighborhoods, Ireland hold his IEEE Globecom audience here.

"When we were done with the rollout of Project Pronto, we had some 40,000 'huts,' or neighborhood gateways, all requiring remote power management," said Ireland, who also serves as SBC's senior executive vice president for services. "One reason we've defined 1.5 Mbits as a sweet spot for residential broadband is that once you go beyond that speed, it gets enormously expensive to deploy."

Long term, he said, "the end game is passive fiber pushed very far into the network."

SBC is running passive optical network trials "in some California subdivisions," said Ireland. "PON is for new buildouts only right now. Still, the day will come when the passive combiner will beat out active electronics in delivering broadband services."

SBC and Qwest Communications International Inc. were among the service providers trying to push DSL further into the network at lower cost points, using small access multiplexers at remote terminals as well as primary DSLAMs at telco central offices. Like other carriers, both companies have backpedaled from aggressive DSL plans in recent months.

Ireland conceded that cable modems still have a lead over DSL lines, with 7 million subscribers to DSL's 4.5 million.

But Ireland said that as the regulatory environment improves along with the economy, the incumbent carriers expect to see a more favorable outlook for residential service in the United States. Even now, SBC discounts any talk of a drop-off in DSL demand. Ireland said new-subscriber tallies in the fall were the highest in SBC's history.

The economy has affected how fast and wide the incumbents wanted to expand DSL service, he said, but it has not killed interest.

Broadband abroad

Nevertheless, many equipment vendors and international carriers are putting the bulk of near-term efforts in such countries as South Korea, where broadband connectivity now reaches 14 percent of residential customers, compared with slightly less than 4 percent in the United States. Ireland said the expansion of broadband service has been a policy of the South Korean government.

SBC has examined alternative broadband access technologies, such as satellite access and fixed broadband wireless, but Ireland said that DSL and cable modems appear to be the only near-term options with growth potential, using existing physical infrastructure. Also, DSL pricing strategies must be adopted to reflect the fact that 1.5-Mbit/second downstream service is the most cost-effective to deploy.

Luckily, Ireland said, T1 speeds seem to meet a broad range of consumer demands, and at a viable monthly subscription price.

Ultimately, Ireland said, the solution is fiber distributed to businesses and neighborhoods via passive splitter/combiners, although for now, such passive optical networks make sense only for new construction projects. If carriers tried to trench existing neighborhoods for passive optical fiber, the costs would be prohibitive, Ireland said.

Typical multiplexing factors for a viable PON would be 12:1 for business customers, he said, and 32:1 or even 48:1 for residential customers.