Ever since companies began supplying employees with mobile devices, the BlackBerry line of smartphones fit the bill nicely. The devices gave end-users access to corporate email and data and provided the IT department with a high level of control.

But, according to TechTarget, the traditional model has continuously deteriorated with the release of more powerful, consumer-based devices. It started with the release and eventual rise of the iPhone in 2007 and has only continued as smartphones based on Google's Android mobile operating system have taken center stage.

According to the report, more devices equal more complexity for cellular expense management.

"Research In Motion's BlackBerry has been the business smartphone standard for more than a decade, thanks to the high level of control it gives to administrators. But more consumers are now buying their own smartphones, such as Apple's iPhone, or devices with Google's Android or Microsoft's Windows Phone 7 operating systems," Colin Steele wrote for TechTarget.

During the past year or so, companies have been forced to support a wide range of devices with wireless expense management and other mobility tools. As more devices have been released to the market, employees are clamoring to use smartphones they are comfortable with to access corporate email and business data.

"Users are driving this endpoint explosion because these devices give them more flexibility in terms of where, when and how they do their work," Steele wrote.

He added that mobile device management must be practiced, in order to control the use of smartphones, protect against security threats and keep an eye on costs.

For example, companies need wireless bill audits to track the contracts that support employee devices. Such tools can help budget managers to identify areas where the company is spending too much or not enough on enterprise mobility.

Apple's iPhone and devices run on Google's Android mobile operating system have been exhibits A and B when it comes to consumerization. Recently, Google's head of Android Andy Rubin announced the platform now experiences 500,000 new activations daily. Just last fall, Google announced that more than 300,000 Android-based devices were activated each day. By comparison, Apple said more than 200,000 iPhones are added on a daily basis.