Mobile cell phone interceptors and scanners will allow you to intercept and record (if you buy a separate recorder) mobile phone conversations automatically, at the push of a button or you can program it to intercept pre-determined numbers.
What you use it for is up to you, but please note that listening in on someone else's conversation could be illegal in your country ...therefore, please make sure that you adhere to the laws.
Most countries have tough laws against eavesdropping; so you could get into trouble if you are not authorized to use it.
Scanning and intercepting cell phone conversations require the use of specialized equipment and the top of the range interceptors are usually sold only to government agencies.
They are extremely expensive ($300 000+), but they are also the best and highly sophisticated.
The cell phone scannners and interceptor described on this page are much more affordable, especially if you only plan to use it a few times.
Cell phone scanners:
Both models have the ability to intercept and record (you can attach them to any tape or digital recorder) cellular conversations, but the AU 286 only allows random scanning of phone numbers. (AU 286 intercepting range = 5 miles).
It's cheaper than the Au 288 interceptor but you have no control over who you want to listen to.
The AU 288 interceptor allows you to store up to 20 numbers, which will automatically intercept both sides of the conversation once the specific number is activated. (Intercepting range = 10 miles).
Mobile cell phone interceptors like the Au 288 make use an A and B system that defines the regions where this interceptor can be used.
Other listening devices
An alternative to a cell phone scanner is to make use of a Q-phone. It works like a listening bug, because when you call the Q-phone, you will be able to listen in on background sound, without the other person being aware of it.
The only disadvantage is that you have to give this phone as a present to someone else or you will arouse suspicion.
Once again, if you use cell phone scanners, mobile cell phone interceptors or any other listening device, please make sure that you stay within the law.