Earlier today we told you that the iPhone 4S has been the top-selling smartphone for all three of Apple’s US carrier partners for the last 6 months. The information came from a Canaccord Genuity investor note that was sent out to shareholders this morning.

Now, AllThingsD is pointing to another part of the report that also provides some interesting data. Not only is Apple’s handset the top-selling smartphone here in the US, but some carriers are actually selling more iPhones than all other smartphones combined…

AllThingsD reports:

“Our March checks indicated the iPhone continues to extend its market share gains,” Canaccord Genuity analyst Mike Walkley writes in a note to clients today. “In fact, we believe iPhones are outselling all other smartphones combined at Sprint and AT&T and selling at roughly equal volume to all Android smartphones at Verizon.”

It’s not hard to figure out why the iPhone appears to be extra popular with these two carriers. Since the original iPhone launched back in 2007, AT&T has been somewhat of a goto carrier for iPhone buyers. And Sprint just became an official partner last Fall.

Still, to think that Apple is selling more handsets than multiple Android manufacturers, Windows Phone partners, and RIM combined, is absolutely insane. Especially when you consider that Apple has only been in the cell phone business for 5 years now.

[9to5Mac]