Reacting to the decision, India's IT-enabled services sector said the ruling of the federal court is a boon for the country's ITES sector.

The National Association of Software and Service Companies said the companies in the telemarketing space would benefit from the US verdict as the earlier regulations had put some companies under pressure.

"This move will help telemarketing companies. They were restricted by the Federal Trade Commission regulations. We are waiting to see the complete impact of this development," said a Nasscom functionary.

"Companies who were depending on telemarketing were hurt by the FTC ruling. This also shows that the companies need to diversify the services offerings and good customers," said Rohit Kapoor, president and chief executive, EXL Services.

The Direct Marketing Association, the coalition of telemarketers that challenged the rules, issued a statement saying it was grateful for the decision.

The FTC adopted its do-not-call rules last December.