The company sent a letter last month to customers in Washington and Oregon alerting them that it charges $4.95 per month for each IP (Internet Protocol) address.
AT&T Broadband plans to enforce the multiple IP charges nationwide, said Sarah Eder, a company spokeswoman. She did not know the timetable for implementing the plan, however.
Customers typically use the multiple addresses as a cheap way to share Internet access among multiple computers in a household. Some AT&T Broadband customers have been able to use multiple addresses without paying for them because the company was not monitoring their use.
"As a result of recent changes made to the AT&T Broadband Internet network, some customers may be currently receiving additional IP addresses without subscribing to our multiple IP service," the company said in its letter to customers. "If you are such a customer and would like to continue receiving additional IP addresses, you will need to subscribe in order to avoid disruption of service."
AT&T Broadband has charged customers to add multiple IP addresses to their service since 1996 when it was known as TCI, Eder said. But in the wake of Excite@Homelast year and the switchover of many of its customers to AT&T Broadband's network, the company did not monitor its network as closely for customers using multiple addresses, Eder said. Less than 5 percent of the company's 1.8 million customers are using multiple addresses without paying for them, she said.
"There were certain tools we didn't have on our network for the sheer ease of migrating (the Excite@Home customers)," Eder said. "We are cleaning up our network. We have a better system and better tools."
The question of whether customers would be able to have multiple IP addresses at all was one of the many issues raised by Excite@Home customers last fall when they werefrom the company's network to the networks of cable providers such as AT&T Broadband. In all, AT&T picked up about 850,000 Excite@Home customers. The action forced the company to operations.
Oluf Nissen, a software designer in Cupertino, Calif., said he discovered by accident about six months ago that he could hook up multiple computers to his AT&T Broadband connection. He eventually had four computers sharing the connection via a networking hub.
But earlier this week, the extra IP addresses he was using stopped working, Nissen said. An AT&T Broadband customer service representative told him that the company had begun to enforce charges on multiple IP addresses. Nissen doesn't plan to subscribe to the service. Instead he plans to just buy a router.
"I can?t say that I blame them (for charging)," Nissen said. "It's a bit inconvenient for me, but it may turn out to be good. I'll have to buy a router, but that means I'll have a private network and file sharing."
Eder said she didn't know why Nissen's multiple addresses were cut off since the company had not started enforcing its policy in California.
"Whatever is happening with that person is unrelated," she said.