Stephan Witteler

O3SIS IT AG provides software solutions providing personal mobile data applications and enabling technology to 1st tier mobile network operators. It's managed service provides for a complete outsourcing of mobile data applications including hosting, operations and maintenance and customer care. It's flagship product 'Unified Mobile Directory (UMD)' is a high-end address book, synchronization and application integration platform. The company was founded in 1996 and is headquartered in Overath, Germany.

T-Systems International GmbH engages in the development, implementation, operation, and marketing of client- and industry-specific solutions in the information processing and telecommunications sectors. These include security, data processing, information management, training, and consulting services. The company was founded on August 30, 2004 and is headquartered in Frankfurt, Germany.