Do you know mobile phone jammers are illegal?-www.wirelessphonejammer.com

Do you know mobile phone jammers are illegal?-www.wirelessphonejammer.com
I am a fun of mobile phone jammers, I bought the mobile phone jammers from a mobile phone jammer manufacturer---Beijing Signal Knight---www.wirelessphonejammer.com, I bought a pocket size mobile phone jammer SK-16A and a medium power mobile phone jammer SK-3. They are very good, and help me to bolck the annoying phone calls in the Lib, Lab, meeting room, and hospital. But there is a problem, someone told me it is illegal in most countries, could you tell me the reason? Why i can not use the mobile phone jammer?

I think it will be very helpful for me.

Best regards,

www.wirelessphonejammer.com