Extending this longstanding agreement reflects both companies' commitment to iDEN technology as a best-in-class platform for push-to-talk (PTT) services.

ENGADGET: Sprint inks another three years' worth of iDEN infrastructure support with Motorola, 'several' new phones coming in Q1

The Sprint Direct Connect launch in October 2011 ushered in the next generation of PTT service from the company that pioneered push-to-talk.

ENGADGET: Where you at? Sprint Direct Connect Now brings push-to-talk to select Android devices

So are lots of other investors, from private-equity funds to oil companies, such as Thailand's PTT.

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