An internet "fable" gives a number to call when you're being pulled over but don't feel safe stopping.  It's BS.

A common internet story tells of a young girl being pulled over by an unmarked police car. Her parents had warned her to never pull over in remote locations and to keep driving to a safe spot while dialing ... depending on which version you read ... either 77 or 112 to let authorities know what she was doing. The unmarked car turns out to be fake and the 112 operator alerts real cops who save the girl from a serial rapist.

The number doesn't work according to Snopes.com.

Some people do impersonate police though so, what should you do?  Some states have special numbers to contact authorities but, your safest bet is to just call 911.  Explain to the operator what you're doing and then follow their instructions. They'll get word to the cop and, if it's for real, you won't be penalized.  More importantly, if it's NOT for real, you won't be harmed!

For more tips on spotting fakes, click here.