Scientific-Atlanta Inc., the city’s first high technology company that was established more than 30 years ago, and Germany’s international powerhouse, Siemens AG, have agreed to a joint venture for development and worldwide marketing of telephony-over-cable products.

Specifically, Scientific-Atlanta will be working with Siemens Public Communications Network Group, which is its parent company’s largest group. In North America, the group is represented by its U.S. company, Siemens Stromberg-Carlson, the public network systems supplier.

Scientific-Atlanta and Siemens said the agreement marks the next step toward implementing IMMXpress, an interactive multimedia network that combines various network management, broadband communications and computing technologies. The IMMXpress alliance also involves Sun Microsystems.

Under the agreement, Scientific-Atlanta is to contribute engineering and technical resources as well as certain intellectual property, while Siemens is to contribute capital, technical and human resources. Initially, Scientific-Atlanta will manufacture the product.

James F. McDonald, Scientific-Atlanta president, says Siemens provides his company with strong global commercialization capabilities for telephony-over-cable products.