Microsoft Corp. and France Telecom SA, one of the world's largest telecommunications operators, announced a partnership under which they will develop products and services.

The alliance illustrates Microsoft's determination to penetrate the telecom market. As people increasingly interact with the Internet with their telephones and television sets, rather than the personal computer, the company wants to make sure that its software stays central.

France Telecom, meanwhile, sees such partnerships as key to its efforts to transform itself from a traditional phone company into a provider of a broad range of services.

The companies said they will develop two joint projects, to which they have each dedicated dozens of engineers. One is a series of phones based on Microsoft software that uses Internet-based services known as voice over Internet protocol, or VoIP. That includes a hybrid handset that customers can use as a cell phone and that will switch to the Internet network when they are home.

The companies said it will be 12 to 18 months before the product is launched.

The second project is developing software that allows operators to provide various services to customers that combine voice, video and data. Theoretical examples include a service that would allow the home user to access an instant messenger on a television screen to discuss with a friend something they just watched. Or, perhaps they could send a video clip to another friend's cell phone. It will probably take a year or two for that product to be launched.