That's likely iPhone related because it's the same weekend Apple's next generation of the smartphone is expected to go on sale, TmoNews said, citing unnamed sources.
T-Mobile did not immediately return a request for comment on the dates, CNET reported.
T-Mobile was the last major U.S. carrier to offer the iPhone, only recently adding the Apple devices to its lineup.
Employee vacation blackouts have in the past been a good clue of when a major product is expected to launch; last August both Verizon and AT&T put such staff vacation blackouts in place beginning Sept. 21, which turned out to be the day the current iPhone went on sale in nine countries.
Apple is expected to debut its new phones at an event Sept. 10, with a release to follow shortly thereafter -- with many believing T-Mobile may have just let that cat out of the bag.