Pacific Telesis and NTT agreed to exchange ideas.

Nippon Telegraph & Telephone, which last year set up an office in Los Altos, Calif., to complement an East Coast office in New York, signed separate cooperative agreements with New York-based Nynex and Pacific Telesis International, a unit of San Francisco-based Pacific Telesis Group. Taketo Suzuki, senior director of NTT’s California office, said the pacts represent “an initial stage” for exploring possible joint ventures outside the United States.