[Jigsaw John]

I don't have time to read all that from the link you provided.

Are you saying Radio Shack sells scanners that can readily monitor cell phones and monitoring cell phone conversations is not illegal?

[petercooper]

I scanned the article. Yes it seems Radio Shack and other sell the equipment. Legality is another issue- probably varies from state to state.

[IamConservative]

The vast majority (if not all by now) of cell communication is digital and sounds like a modem because in fact it is a CDMA or GSM modem.

Many residential phone communications are transmitted to the central office over open air frequencies easily scanned by anyone with a scanner.

While not practical to enforce, it is illegal to monitor these frequencies. It is certainly illegal and enforceable to act on what you hear.