Scanner 911 for iPhone and iPod touch by Matthew Pease can access police, fire and emergency medical service (EMS) from over 1,400 sites from the U.S., Canada, and a few other countries. Basically, it puts a global scanner in your pocket. While most of the chatter will be unintelligible or irrelevant, it could come into good use during an emergency.

For the U.S., the app shows the sources by state, their popularity, and whether it's a police, fire or EMS channel. The app works over Wi-Fi or the AT&T data network.

Default Main screen with speaker grill instead of map

Tabs underneath show the list of states from which radio source can be selected, the hottest 100, the ones near you if you allow location services (uses GPS, not Wi-Fi hotspots, so it helps to be outside), a list of saved recordings and More...

More... contains the setting that enables the map view, but the map is not particularly precise -- just a high level view of the region. If you see the speaker grill instead of the map, you'll need to go into Settings to turn the map on.

One of the nice features is the ability to record a session as well as bring up a list of police codes. A Help page at the bottom of codes provides help, an FAQ -- including how to make recordings -- and feedback to the developer.

The list of codes is several pages long

The stream is buffered, so you can pause and resume. If the source if offline, it's noted in the source list. You also have the option to continue to let the audio run in the background even after you quit the app.

All in all, this is a fairly nifty app in its concept. At first, it'll be fun to listen to police conversations in a state far away, perhaps your home town. However, a lot of that chatter has clicking, noise, dropouts, and the speakers make heavy use of police codes. So it'll require some long term practice if you want to learn to decipher what's being said. If not, then you may quickly tire of the app.

Where the app could come in really handy is during a local emergency, such as a forrest fire or other natural disaster. Then you may discover this neglected app again and be glad you have it.

Some customers reported problems with an iPhone 3GS, but it installed and ran fine on mine. For US$0.99, you'll get your money's worth if you have an interest in tuning in to see what's going on elsewhere on these police frequencies. Hopefully, you'll never need it for personal use in a natural disaster. But it's nice to know it's there.

The one thing I didn't like was that when launched, the source list comes up instead of the list of favorites -- or the last one played -- and then an added link to the full list. That's perhaps a matter of taste. Otherwise, the app is very nicely designed, works as described, and has a lot of nifty features.

Scanner 911 by Matthew Pease is $0.99 and requires iPhone OS 3.0 or later.