Alternatives to mobile phone jammers
Although the law clearly prohibits the use of cell phone jammer to actively disrupt cell phone signals, there are no rules prohibiting passive cell phone blocking. This means using things like wallpaper or building materials embedded with metal fragments to prevent cell phone signals from entering indoors or outdoors. Some buildings are designed to accidentally block radio signals due to thick concrete walls or steel skeletons.
The company is developing devices that can control mobile phones without "interfering with the signal." One device sends incoming calls to voice mail and blocks outgoing calls. The argument is that the phone will still work, so technically it won't get stuck. As of April 2005, the FCC has not yet made legal regulations for this area.
You can use a cell phone alarm to indicate the presence of a cell phone signal. These have been used in hospitals, and mobile phone signals may interfere with sensitive medical equipment. When a signal is detected, the user is required to turn off the phone.
In order to provide a low-tech solution, Coudal Partners, a Chicago-based design company, established SHHH, the Handushed Hushing Association. On its website, you can download notes to send to people who are having annoying mobile phone conversations, indicating that you are not interested in what they are talking about.