Another month, another peek at Windows Phone handset usage courtesy of AdDuplex. This month, low-end Lumia handsets surge yet again, Nokia comes on strong in the United States, Windows Phone 8 usage finally exceeds Windows Phone 7 usage, and the first Windows Phone 8 device for Sprint appears in testing.

As you may remember, AdDuplex bills itself as the largest cross-promotion network for Windows Phone and Windows 8 apps, empowering developers and publishers to promote their apps for free by helping each other. And each month it provides a tantalizing glimpse at which Windows Phone (and Windows) devices people are actually using.

Some trends from this month’s report, which will be live tomorrow, include:

Nokia Lumia 620 and 520 are surging. While the top three Windows Phone handsets worldwide (Nokia Lumia 920, 710, and 800) remaining unchanged month over month, the remainder of the top five is now occupied by two fast-surging newcomers. The Lumia 620 hits at number four and jumps to 9.4 percent usage share, while the Lumia 520 rocketed to number five with 8.4 percent usage share. The message? Nokia’s strategy of creating high-quality but inexpensive low-end devices is working.

Top 5 are all Nokia. Once again, the top five Windows Phone handsets are all made by Nokia: Lumia 920 (12 percent), Lumia 710 (11.6 percent), Lumia 800 (10.6 percent), Lumia 620 (9.4 percent) and Lumia 520 (8.4 percent). Actually, the top eight are all Nokia devices: The Lumia 610 (7.2 percent), Lumia 820 (7.1 percent), Lumia 900, HTC Windows Phone 8X, and Lumia 720 round out the top ten.

Nokia makes slight gains. I noted last month that 80 percent usage seems like the natural plateau for Nokia overall as they’d been stuck at that figure, roughly, for several months. But this month, Nokia actually jumped somewhat to 83 percent usage, largely at the expense of Samsung. HTC also made small gains at Samsung’s loss. My take: Samsung is quickly becoming an also ran after making some of the very best Windows Phone 7.x handsets.

Windows Phone 8 finally out-performs its predecessor. AdDuplex notes that this is the first time that Windows Phone 8 handsets were in use more often (53 percent of the time) than Windows Phone 7.x handsets (47 percent). (In the US, 70 percent of these handsets run Windows Phone 8, however.) And that leads to a truly interesting statistic…

Nokia is actually coming on strong in the United States. In the past, the story was that Nokia wasn’t as competitive in the US as it was internationally. But if you look just at Windows Phone 8 handsets (the “now” as opposed to the “past”), something interesting emerges: In the US, fully 77 percent of those phones are made by Nokia, with HTC pulling in 22 percent and Samsung drifting off with just 1 percent. So it's almost identical to the full world market. (Note: These figure were updated by AdDuplex and were previously a bit different. --Paul)

Verizon trumps AT&T. With the release of the well-received Lumia 928—see my review—Verizon Wireless has pulled ahead of AT&T with 43 percentage usage among Windows Phone users (compared to 39 percent for AT&T and 14 percent for T-Mobile.) That said, T-Mobile just got the equally well-received and budget-priced Lumia 521, so next month could be interesting too.

New unidentified devices. As is often the case, AdDuplex notes the arrival of some mysterious new Windows Phone handsets in this month’s report, and one of them, this month, is coming to Sprint users. These new phones include the NOKIA RM-955_apac_prc (China, WXGA screen), NOKIA LC4301 (test device running Windows Phone 8.1), NOKIA P5238 (test device), HTC HTCPO881 (aimed at Sprint, with WVGA screen), HUAWEI H887L (US and China, WVGA screen), HUAWEI W2-T01 (a successor to the Huawei W2, WVGA display), and the SAMSUNG SGH-I187 (Korea and US, 720p screen).