AT&T spending more to launch the Lumia than it did on the iPhone (Updated)

AT&T is investing heavily in the Nokia Lumia 900 and spending more money on the Windows Phone handset launch than it did on the iPhone, according to a report in Ad Age.

The wireless carrier may be spending as much as US$150 million to advertise the phone, which is an AT&T exclusive. This is a lot of money, even for a carrier like AT&T and leaves everyone wondering why it would spend so much on a platform that is losing market share.

Ad Age claims that, after years of exceptional sales, AT&T's smartphone growth is slowing now that the iPhone is available on Verizon and Sprint. Rather than rely only on the iPhone alone, AT&T is looking for another exclusive, blockbuster phone that'll boost its subscribers. Right now, according to Ad Age, that phone is the flashy Nokia Lumia 900.

Update: A report from The Verge calls into question the $150 million figure from Ad Age. Sources familiar with the matter say the actual dollar amount is much lower than $150 million and more in line with any high-profile phone launch.

The Verge also points out that Ad Age uses a comScore report to claim that AT&T's smartphone penetration is slowing. A look at the quarterly earnings shows that Verizon's smartphone ownership grew 5 percent between Q3 2011 and Q4 2011, while AT&T increased a very close 4.2 percent.