While the site Eveadam has listed does sell amplifiers the company is a wholesale comapny based in China. The links that Eveadam provided lead you to jamming devices. In the US you will need a special permit to use and it is illegal to use, own or sell.
Cell phone blocking devices are used by federal officials under certain circumstances. Privacy rights of property owners may affect the policy and application of law within buildings. The FCC may issue a permit that waives the law for private use. For radio communications, it is illegal to operate, manufacture, import, or offer for sale, including advertising (
Communications Act of 1934).
[9] Blocking radio communications in public can carry fines of up to $11,000 or imprisonment of up to one year.
[10] The
Homeland Security Act of 2002 may override the Communications Act of 1934.
[11]Cell phone blocking devices are used by federal officials under certain circumstances. Privacy rights of property owners may affect the policy and application of law within buildings. The FCC may issue a permit that waives the law for private use. For radio communications, it is illegal to operate, manufacture, import, or offer for sale, including advertising (
Communications Act of 1934).
[9] Blocking radio communications in public can carry fines of up to $11,000 or imprisonment of up to one year.
[10] The
Homeland Security Act of 2002 may override the Communications Act of 1934.
[11]