The US number three mobile operator Sprint Nextel has dropped 1,000 customers who phoned its customer service lines too often.
Sprint Nextel says the callers were making "unreasonable requests"
The company sent letters to the customers saying their service agreements had been terminated.
They were given 30 days to transfer their numbers to other providers.
Sprint said that the customers concerned had been calling its help lines an average of between 40 and 50 times per month.
"In some cases, they were calling customer care hundreds of times a month for a period of six to 12 months on the same issues, even after we felt those issues had been resolved," said Sprint spokeswoman Roni Singleton.
She added that some of the customers had repeatedly called to ask for information about other people's accounts, which the company is not allowed to reveal.
Sprint waived the final balances on the cancelled accounts.
The company has just started a marketing campaign to attract new subscribers.
Figures for its most recently reported quarter showed that it had 600,000 new customers in the three month period, compared with 1.2 million for AT&T and 1.7m for Verizon.