MISHAWAKA -- Many of us have made the mistake of leaving our cell phone keypad unlocked in our purse or pocket, then accidentally dialing a number. Now, dispatchers say millions of people mistakenly dialing 911 is becoming a safety problem.

When the calls come in, dispatchers don't know if it's a legitimate emergency until they pick up. Dispatchers are required to call a number back if they don't talk to a person on the other end.

Those abandoned 911 calls come from two main sources: hangups and phantom wireless calls.

Mishawaka 911 Dispatch Coordinator Charlene Monges said the problem with phantom calls is the automatic number and location indicators don't always work with cell phones. The computer screen only shows an approximate location of the call.

That means if dispatchers don't have a number, they can't call back.

"Part of the problem is if our operators are tied up answering and calling back all of these hangup calls, if someone calls with a real emergency, it's possible that their help can be delayed," explained Monges.

In 2007, Mishawaka police and fire dispatchers called back 3,138 abandoned 911 calls. Out of those, 409 (13 percent) were phantom cell phone calls.

There are steps you can take to make sure you're not part of the phantom 911 problem.

- Make sure your key lock is on if your cell phone is in your purse or pocket.

- If you mistakenly dial 911, stay on the line to let the dispatcher know it was an accident.

- Remember any cell phone can dial 911, even if the service has been disconnected. So you shouldn't let small children play with them.