What you can do is set some policies about the use of such technology for work purposes. You can require employees to have a minimal amount of insurance if they are expected to drive for the company using their vehicles, for example, and to have a valid driver's license. Likewise, you can cap the per-minute rate you will reimburse for long-distance and international calls made from employees' phone lines.
In the context of BYOD, that's the same as telling employees they can use their personal devices for work access if their devices meet your mobile management policy requirements, such as agreeing to be remotely locked or wiped if the device is lost and to have a password and encryption enabled.
You can even go so far as to make the furnishing of specific technology a spelled-out job requirement, just as you can insist that an employee buy and clean their uniforms for jobs that have them (pilots, police, wait staff, nurses, and so on). For example, you may require salespeople to bring their own smartphones, with a choice of iPhone or BlackBerry. But those devices belong to the employees, as do their phone numbers.
If you want to keep the phone number so that a salesperson can't be reached easily by your customer if that salesperson quits, then you provide the phone and number yourself.
This principle also applies to social media use. If you expect employees to tweet or participate in social networks such as Google+, Pinterest, and Facebook, you provide the account if you want to own the handle and control the content. But if you want to leverage employees' personal networks, such as by encouraging them to tweet, post good news about the company, or reach out to contacts via LinkedIn, you're asking for a favor and can at most specify how you want them to deliver on that favor.
If you don't trust the employees to do so professionally, you should have a policy that forbids mention or discussion of the company and its competitors in any public medium (like Apple does) -- and hire your own staff to do PR via social media social media accounts you own.
What worries me is how cavalier so many companies are about treating theier employees like mindless robots -- or worse as work slaves -- demanding all and giving little. A great example of that is the shocking trend of some companies requiring job applicants' Facebook passwords. My response to that would be unprintable (the polite form would be "You give me yours and I'll give you mine"), and it's no surprise that legislatures are moving to ban the practice. The ony good thing about this form of corporate slave-owner mentalty is it lets you know whom to not work for, and whom to sue or boycott.
Even with the egregious Facebook example put to the side, too many companies assume they own their employees, expecting to use and even control their personal resources, time, and even conversations -- but not being as flexible or open in the reverse.
The bottom line is you can't have it both ways and make employees give you their property because it's convenient for you to do so. If you want actual ownership, you pay for and manage the asset. Otherwise, leveraging employee assets means setting policies that protect you but honor the fact those assets aren't yours. Remember: Slavery is illegal, so you rent employees, not own them -- or their technology.
This article, "Who owns what when employees use their own tech," was originally published at InfoWorld.com. Read more of Galen Gruman's Smart User blog at InfoWorld.com. For the latest business technology news, follow InfoWorld.com on Twitter.