As mobile carriers prep for the highly-anticipated iPhone 5 release, the rumor mill continues to churn out more gossip and leaks. The latest rumor claims that carrier T-Mobile has leaked the launch date of Apple's iPhone 5. The news comes as a surprise, since T-Mobile does not even sell the smartphone.

On Monday, Aug. 27, T-Mobile's unofficial blog TmoNews acquired an internal training memo, which indicates that the carrier is instructing its employees to "sell against the iPhone". The two leaked screenshots resemble corporate e-mails to the carrier's employees.

The T-Mobile campaign is slated to start on Sept. 21, which is the rumored release date of the fabled iPhone 5. The strategy suggests that T-Mobile is unlikely to have the next-generation Apple smartphone on board.

"Perhaps it's coincidental that the information for employees to utilize against the iPhone will drop on September 21st, a date being tossed around as a possible release date for the next-generation iPhone. Perhaps it's just coincidence, but we can't envision a scenario in which T-Mobile would prepare their employees to sell against a product they are about to receive," noted the blog.

Not having the iPhone, yet again, can affect the carrier in a major way. The iPhone's popularity in the U.S. is phenomenal and consumers may likely shift to other carriers like AT&T and Verizon who offer the Apple smartphone. Moreover, even though Android smartphones are gaining popularity, T-Mobile's deployment of the aggressive "sell against the iPhone" tactic may not be a cakewalk.

Whether the strategy is based on release date rumors or T-Mobile knows something that others do not is anybody's guess.