T-Mobile finally has a compliant partner to merge with now that the sometimes standoffish MetroPCS board approved the unification of the two no-contract companies.

The T-Mobile/MetroPCS deal marries the fourth and fifth largest carriers in the U.S., bringing the 8.9 million MetroPCS subscribers over to T-Mobile's existing 33.4 million customer base.

"We are pleased with the outcome of today's vote and thank all of our stockholders for their support," said MetroPCS chairman and CEO Roger Linquist in a press release.

"Our combination with T-Mobile will create the value leader in the U.S. wireless marketplace."

T-Mobile, MetroPCS results

At a combined 42.3 million subscribers, the combined T-Mobile and MetroPCS will still be in fourth place.

The company, which will retain the name T-Mobile, will trail third-place carrier Sprint by more than 13 million customers.

But the merger isn't all about total customer numbers. It'll also bring about a greater rollout of 4G LTE coverage for the unified subscriber base.

New phones and T-Mobile's no-contract plans will also be a benefit to customers thanks to the two telecom companies working together.

T-Mobile's long road to find a partner

This isn't the first time that T-Mobile has had trouble getting a merger approved.

The carrier was involved in an AT&T acquisition worth $39 billion that was eventually blocked by the Federal Communications Commission in 2012.

AT&T finally abandoned its year-long bid for T-Mobile USA, which was ultimately good news for second- and third-place rivals, Verizon and Sprint Nextel.

This merger, which takes effect at the close of April 30, isn't as much of an immediate threat for the top three carriers.

However, with the T-Mobile iPhone 5 launch this month and no-contract plans, T-Mobile living up to its "Stick Together" slogan may be its best move to keep its customer based from plunging any further.