But company executives said they were happy with its growing user base and dominance of the Internet calling market.

Among business users, meanwhile, Japanese companies appear to be leading a migration to Internet calling.

Once that happens, companies can start to use Internet calling to communicate between their own offices and customers and suppliers.

Phone companies, too, are planning to offer lower-cost Internet calling and expand bundled services to attract customers.

The Skype products all work differently to allow Internet calling.

Skype, the Internet calling service that started as a way to call friends at no charge, is pushing into the workplace.

Over all, the Internet calling business is booming.

Those gaps in service may alienate customers, analysts said, if cable companies introduce Internet calling too quickly.

But the charges for the Internet calling plan do not cover the cost of high-speed, or broadband, connections.

Equipment from Ooma offers free domestic Internet calling; international calls are about 2 cents a minute.