Verizon iPhone 4According to The NPD Group, which does not track corporate/enterprise mobile phone purchases, Apple iOS share declined 4 percentage points to comprise 19 percent of unit sales in Q4; RIM OS fell 2 points to tie Apple’s 19 percent; Windows Mobile, Microsoft’s legacy OS, fell 3 points to 4 percent, as the new Windows Phone ’07 OS debuted at 2 percent; and Palm’s WebOS held at 2 percent. Android was up 9 percentage points to 53 percent ahead of Apple iPhone’s Verizon Wireless debut.

Despite buy-one-get-one promotions at both AT&T and T-Mobile, the Windows Phone 7 OS claimed less market share than its predecessor, Windows Mobile, for which handsets are still available at all four major U.S. carriers. Windows Phone 7 also entered the market with lower share than either Android or webOS at their debuts, according to NPD’s Mobile Phone Track.

Ross Rubin, executive director of industry analysis for NPD said int he press release, “Android will encounter greater competition this year, however, as Apple’s iPhone 4 — the best-selling handset in the U.S. — debuts on Verizon Wireless.”

Based on U.S. consumer purchases of mobile phones in Q4 2010, for the first time there were no feature-phone handsets in NPD’s top-five ranking as all top-selling mobile phone models were smartphones.

Top Five Handset Models Were All Smartphones in Q4 2010
1. Apple iPhone 4
2. Motorola Droid X
4. Apple iPhone 3GS
5. Motorola Droid 2

Source: Mobile Phone Track – NPD’s consumer tracking of U.S. consumers, aged 18 and older, who reported purchasing a mobile phone. NPD does not track corporate/enterprise mobile phone purchases.

MacDailyNews Take: NPD does not track corporate/enterprise mobile phone purchases, a large market segment where Apple is reportedly doing very well, so keep that in mind when perusing theses “market share” numbers. They measure a specific portion of the U.S. mobile phone market (consumer) that favored Android which was heavily pushed and BOGOF’ed by Verizon before they attained a deal with Apple for the real iPhone. As Rubin mentions in the press release, everything changes going forward, including the portion of the market covered by NPD.

UPDATE: 4:15pm EDT: And, oh, Windows Phone ’07 – heh, we totally forgot about it – is, as we predicted, a dud. Pray for Balmy.