Microsoft could be making a big mistake with its new smartphone

Microsoft could be making one big mistake in the roll-out of the new Lumia handsets: carrier exclusivity. 

The company confirmed to WMPowerUser that the smaller of the two new handsets, the 950, will be exclusive to AT&T, a move that can indicate that a phone will underperform commercially, as less customers are eligible to upgrade or use it. 

"We're refocusing our channel strategy, narrowing it in the short-term and planning for broader operator availability long-term," the company said. "While there was interest across the board from U.S. operators, currently we've made the decision to have AT&T carry the Lumia 950." 

Previous phones that have been AT&T exclusives include the Nokia Lumia 1520, the HTC First (also known as the "Facebook Phone"), and the BlackBerry Torch 9810. None of these phones went on to be commercial best sellers, and the HTC First reportedly sold just 15,000 units. Keeping the 950 an AT&T exclusive was described by PC World as a "disaster." 

Even the iPhone, which was sold exclusively in the US by AT&T until 2011, became the success it is today when Apple decided to open it up to all carriers at launch.

By making the 950 a carrier exclusive, Microsoft is hampering the success of the phone. Users who may have bought the devices but are on Verizon - a network with around 135 million customers in the US - or T-Mobile - which has around 60 million customers - cannot easily access the 950, and will likely continue using an iPhone or Android device. 

T-Mobile CEO John Legere took to Twitter to describe the decision as "total b******t" encouraging Microsoft to "wake up." 

The two phones will be sold unlocked via Microsoft's online store, but this is unlikely to boost sales to any great extent. Microsoft's mobile offerings already struggle enough with marketshare and the company limiting the potential customer base is unlikely to help this. 

Business Insider has reached out to Microsoft to ask about the exclusivity deal and how it will affect sales of the handset. We will update the post when we hear back.