Federal officials warn cell phone-centered lives may open up new long-term privacy issue

Finance expert Erica Sandberg juggles calls all day every day. So, whenever she is asked for her phone number, it's all about her cell.

"The reason I do use it as my primary number is because it's the one I always have with me."

But Sandberg does not just give it out to friends and clients.

"It's pervasive right now. Every single time you sign up for something, you're going to be asked for your personal information, and very often that includes your primary phone number, which for most people these days is the cell phone number."

Phone numbers on forms aren't new, but Federal Trade Commission experts said today's mobile landscape is different. Whereas landlines change if you move and are associated with everyone in a household, cell numbers may stay with a single person for life.

"And what that means is that the number will be linked to the individual and can be sort of an identifier to tell people how to link other information to that individual," said Robert Schoshinski, Federal Trade Commission.

Think of it this way-- every time you sign up for something or shop online, you fill out information. In some cases, terms and conditions may allow that information to be shared or sometimes even sold to third parties.

"Once you've linked a cell phone number to an individual's name or profile, you can link all sorts of other information that a data broker may have. So, for instance, online browsing habits, online shopping habits, in-person shopping habits," said Schoshinski.

Experts said that information can be used for marketing or even sold again to others interested in the compiled information. Sandberg said she will now think twice before giving out her number:

"I'm certainly concerned about it, and it has made me pause before just randomly writing it out or supplying it on an online form."

One possible solution to adding your primary cell number on forms are apps such as Sideline, Line-2, and BusinessCall allow you to add a secondary line right onto your cell. This way you can separate your personal calls from any other type of business.