masayashi-sonsoftbank
Softbank Corp. CEO Masayoshi Son speaks during a news conference in Tokyo on July 30, 2013. Reuters/Issei Kato

(Reuters) - Japan's SoftBank Corp will soon downsize its Silicon Valley offices, people with knowledge of the matter said, signaling the company won't revive efforts to buy T-Mobile U.S. Inc.

SoftBank subsidiary Sprint Corp dropped its bid to acquire the No. 4 U.S. carrier in August but the companies did not rule out future consolidation.

The Japanese telecommunications company