Real Networks CEO Rob Glaser says that in the future, mobile phone penetration will approach 200% because nobody will be able to find one device that does everything they need it to. I think he’s completely wrong about the reasons, but I do think many people have multiple mobile phones in their future. Most people don’t use any of the features of their mobile phones beyond voice calling, and in the meantime phones are gaining lots of new capabilities. I don’t know anyone who carries multiple mobile phones right now, even in an age where phones are still pretty limited.

I do think, however, that we’ll see people carrying multiple devices in the future because there are advantages to separating their employer-issued phone from their own phone. I was talking to someone a few months ago about their Blackberry, and they told me that they hadn’t yet activated the email access because it connects to their corporate mail server, and as soon as that happened they wouldn’t be able to use it to text their friends. (This person worked for a brokerage firm, and some regulatory requirements required the firm to monitor all employee communications on company-owned devices.)

The Blackberry 8800 doesn’t have a camera, and it’s a feature. A friend who’s an attorney can’t carry a phone with a camera because they’re banned in the federal courthouse, so he’s buying the 8800. So if he wants a camera phone, it’ll have to be on his personal account.

More people are going to want personal mobile phones so that when they’re off the job they’re really off the job. As more and more functions of our work life become portable, we’ll find people going to extra lengths to separate them. When webmail became common, people who used their work email addresses for everything started separating their personal email from their work email. Work-specific instant messaging accounts are becoming increasingly common. You may not want to give the AIM ID you could be using for the next 20 years to a customer you have to collaborate with on a three month project.

As mobile phones become increasingly integrated into our professional lives, we probably will see more people with multiple mobile devices, but mainly so that we can leave work at the office and still call people from the grocery store.