More than 17,600 users in the U.S. Immigration and Customs Enforcement (ICE) are switching to the iPhone as part of a $2.1 million contract with Apple, according to an Oct. 17 announcement.

The BlackBerry has slid in popularity over the past few years, and the device has mainly stuck around through government and business contracts as most consumers opt for smartphones like the iPhone or Android devices.

According to a document explaining why the iPhone was chosen for the contract, Apple's strict control of the hardware platform and operating system as well as the ability to choose a service provider are all reasons the company was selected. Apple also received a full score on “operating system modification detection,” while Android scored a one on a scale from zero to five.

Like many government agencies, ICE relied on the BlackBerry for years before switching to a new platform, more than eight years in this case. Windows 7-based devices were not thoroughly considered by ICE because the organization considered them risky due to their limited use in the market. Operating systems like Linux, Bada, Symbian and Palm were also eliminated from consideration. Android was considered but ICE viewed the open source platform as a security risk.

RIM is still considered the mainstay for government and more than 90 percent of Fortune 500 companies, the company said. "We have 1 million government customers in North America alone who depend on BlackBerry, and more than 400,000 government customers worldwide upgraded their devices in the past year," the company added. "We are committed to the mobility needs of government agencies around the world."