Fifty-four percent of Verizon's Android and BlackBerry users plan to switch to the iPhone when it becomes available on Feb. 10, according to a survey by uSamp (United Sample Inc).

According to uSamp, 25 percent of 727 smartphone users surveyed said they were very likely to switch, while 29 percent were somewhat likely to go iPhone.

Two-thirds of Verizon’s BlackBerry users report they are very or somewhat likely to switch to the iPhone that day, as are nearly half of its Android users.

uSamp said its survey affirmed initial reports of widespread defections from AT&T. According to the survey, 26 percent of current AT&T customers plan to switch to Verizon’s iPhone on the day it becomes available. For now, however, the remaining 74 percent would rather wait than switch.

As AT&T loses its hold on the iPhone, its customers who plan to switch to Verizon have one clear-cut reason: dropped calls (48 percent), carrier coverage (25 percent), product features (22 percent) and other reasons (30 percent).

For switchers among Verizon’s smartphone users, it’s all about the cool features: the interface (60 percent), web browser (58 percent), media (51 percent), memory (43 percent), and camera (41 percent), according to uSamp.

Starting Feb. 10, iPhone 4 on Verizon will be available to all qualified customers at Apple’s retail stores. iPhone 4 will also be available at more than 2,000 Verizon Wireless Communication Stores nationwide.

Meanwhile, Verizon said it ceased online orders of iPhone 4 to existing customers yesterday and ended the most successful first day sales in the history of the company. These initial orders were placed between the hours of 3 a.m. and 5 a.m, it said.

iPhone 4 on the Verizon Wireless network will be available for a suggested retail price of $199 for the 16GB model and $299 for the 32GB model with a new two year agreement.