Sometimes there are limitations even on what_s unlimited. Or at least that_s true in the world of Internet service providers (ISPs). Infinet, a private, Norfolk, Va.-based Internet company that helps newspapers launch and maintain Web sites and provides $19.95 per month online access to many of the papers_ subscribers, recently sent out warning notices to about 1,000 of those customers. The letters told certain offending Netizens that they were commanding too much time while logged onto their "unlimited" online hookups. "According to the terms and conditions of our agreements with users, they were falling into a high-usage definition and we did send them letters identifying that for them," said Susan Kelly-Gilbert, vice president of customer development at Infinet. "We let them know we could terminate our contract with them." Kelly-Gilbert said that almost all ISPs_ contracts with customers identify ways that users may use their accounts in breach of their user agreements. Being online for too many hours on a daily basis, otherwise known as "camping," is one way. Purchasing an individual account and then connecting multiple users to it in a business setting is another. "If that happens, then (ISPs) send out letters like the one Infinet sent," Kelly-Gilbert said. "They identify individuals who may not be in compliance with the terms of contract."