AT&T; Communications has opened a new sales and business support office in the Los Angeles Corporate Center in Monterey Park. The facility, called AT&T; Plaza, serves business customers in the Los Angeles (213) and Hawaii (808) telephone code areas. The center houses about 250 employees who have been transferred from downtown Los Angeles. The offices occupy four floors of the six-story building at 1000 Corporate Center Drive. AT&T; signed a long-term lease valued at more than $5 million in total rent.