AT&T (NYSE:T) probably has gotten more publicity for spinning the word “unlimited” than it has for any of the services it provides. One AT&T subscriber, an iPhone owner named Matthew Spaccarelli, apparently has decided to press the carrier on what it really means to offer unlimited-data service to its customers.

Spaccarelli won a small-claims case that alleged the company was slowing down his unlimited data service. AT&T had been “throttling” unlimited-data users – significantly slowing their download and upload speeds — once they reached the top 5% of data users in their area, for the duration of that month’s billing cycle. AT&T has since revised its approach, saying it would apply the slowdown after 3GB of data consumption.

AT&T offered to discuss a settlement with Spaccarelli, one of about 17 million subscribers still on AT&T’s unlimited-data plan, which the company has since discontinued. But Spaccarelli is having none of it. He is less interested in a settlement, he told the Associated Press, than he is in defeating the carrier in court.

After posting his small-claims and related documents online, Spaccarelli also has been encouraging other AT&T unlimited-data subscribers to copy his suit. Legal settlements, the AP notes, usually include nondisclosure agreements that would force Spaccarelli to take down the documents. Spaccarelli also forwarded a letter to AP in which AT&T asked him to keep quiet about settlement talks.

Spaccarelli has acknowledged, and AT&T has pointed out, that he was using his iPhone to provide Internet access for other devices, in violation of his subscriber contract.

His initial success in court harks back to the small-claims victory by Heather Peters, who sued Honda (NYSE:HMC) because, she said, the company misled her about the expected performance of her Honda Civic hybrid.

In any case, AT&T said it will appeal the small-claims decision.