Meanwhile, "mobile wannabes" are expected to increase to 25% of all employees as smartphones become more popular with consumers, Forrester said.
Enterprises are drastically underestimating the number of workers who will need mobile support, according to a new report from Forrester Research.
The estimated percentage of employees who need mobility support and application access is around 20%, the report said. But companies typically define mobile workers as those who are away from their desks at least one-fifth of the time, telecommuting, or traveling.
What this leaves out is a rapidly growing segment of workers who aren't classified as mobile, but want access to some corporate applications on the go.
"Take, for example, the 25-year-old administrative assistant who spends her day at her desk but wants to keep up with her e-mail and complete her boss' travel expenses during the commute," the report said. "She is not mobile, but wants -- and will expect -- mobility support."
Forrester has categorized this group as "mobile wannabes," and estimated this group accounts for about 6% of all employees. This group will balloon up to 25% of all employees as smartphones become more popular with consumers and as younger workers enter the businesses.
"These millennials are technology natives who enter the workforce with the expectation that companies will support their mobile application needs whether they are formally classified as mobile workers as not," the report read.
The report said mobile information workers -- those who travel frequently or telecommute -- account for 20% of workers today, and that will rise to 34% of all employees worldwide in four years. Mobile task workers represent about 10% currently, and that will increase to 15%. Overall, Forrester estimates 73% of employees will be mobile in some form by 2012.
Additionally, the report found that the line is blurring between using mobile devices for professional and personal activities. Forrester found that 57% of U.S. smartphone owners with full- or part-time jobs currently use their personal handsets for work-related phone calls, and nearly half use their phones to check work e-mail.