Using a license enforcement agent, the French telecom firm has already put six U.S. companies on notice. The six are among some 20 companies that use Turbo coding in applications such as 3G phones and wireless basestations, including cdma2000 and wideband CDMA, France Telecom charges. Makers of so-called DVB-RCS chip sets designed for accessing the Internet via satellite are also a target.

France Telecom is homing in on chip makers that sell devices in which Turbo coding is an integral part of the chip's architecture, whether as software or hardware. Several ASIC suppliers and at least one major DSP maker are among those being sought for royalties. France Telecom said it has 30 patents covering convolutional and block Turbo coding, and is using agents in the United States and France to enforce its intellectual property claims.

"We're focused on the ASIC manufacturers as the point of collecting royalties. But if you're a hardware manufacturer and you're implementing Turbo code in a DSP or FPGA through embedded software we're also looking to collect royalties from you as well," said Erik Johnson, director of sales and marketing for Spectra Licensing Group (Rancho Bernardo, Calif.), France Telecom's licensing agent in North America.

France Telecom is giving target companies two choices: sign an "amnesty" licensing agreement by year's end that forgives royalties on existing chips or equipment that include Turbo coding or take a license by the first quarter of next year and pay either 10,000 Euros ($9,000) or back royalties, whichever is less. Those that refuse these terms will likely be sued by France Telecom for much more later, Johnson said.

"It could be in the hundreds of thousands to multimillions of dollars," Johnson said. "Some chip manufacturers have already made several millions of these chips."

At the same time, France Telecom will also seek agreements with IP providers, including FPGA makers, to obtain lists of customers using the forward error correction scheme. Under this plan, IP providers would not be liable for royalties, but their customers would. So far, San Diego-based iCoding Technology Inc. and TurboConcept have signed on. TurboConcept is also the European licensing agent for France Telecom.

Claude Berrou, credited by France Telecom with inventing convolutional Turbo codes while at the company in 1993, serves as its adviser, Johnson said.

The response by those companies contacted has been mixed. "I've spoken with some manufacturers who've said they would like to evaluate our position. Others would rather ignore it and hope it goes away. But I have no plans of going away any time soon," Johnson said.