British Telecommunications Plc is expanding its alliance with its first Japanese partner, but that partner is not Nippon Telegraph & Telephone Corp. The UK company yesterday announced agreement with its existing partner, trader Marubeni Corp, to form a joint venture in Japan to provide domestic and global communications services. On April 1, a new joint venture, BT Network Information Service, will be formed by combining an existing joint venture, Network Information Service, and BT Japan. The new company will provide companies in Japan with the full range of domestic products and services currently available, as well as offering its customers direct access to the… services from Concert, the two said. The venture will also offer international private line connections, Internet, intranet, video conferencing, Syncordia facilities management services, domestic Frame Relay and voice resale. The integrations puts most of BT Japan’s employees and facilities, and all its customers, into BT Network Information Service, to create one organization with over 200 staff, and 10,000 customers.