Different countries use different cellular frequencies in the world.Here talk about the difference of the frequencies in different countries.

1. The Different Cellular
Frequencies in the World

2. • Different countries use different cellular frequencies in the world.
• In US,the main frequency bands in communications are GSM850,
GSM1900, 3G (850/1900 and 1700/2100) and 4G (Verizon USA 4G,
Sprint Clearwire WiMAX and T-Mobile 4G).

3. • You can see the details from the sheet which lists different bands and
technologies that the main carriers in the US used as follow(from
wikipedia):

4. • In the table the cdmaone and UMTS mean the different generations
of the mobile phone and the different technologies.You can see the
different generations in the table(from wikipedia):

5. • What about the other countries? You may be confused about their
differences.You can see the exact informations from the map(from
worldtimezone.com):

6. • In conclusion:
• GSM 900 / GSM 1800 MHz are used in most parts of the world:
Europe, Asia, Australia, Middle East, Africa in the blue area of the
map.
• GSM 850 / GSM 1900 MHz are used in the United States, Canada,
Mexico and most countries of S. America in the yellow area of the
map.

7. • So if I wanna go to China or Europe,is it that my cell phone cannot
work according to the situation? Don’t worry.
• Many GSM phones support three bands (900/1,800/1,900 MHz or
850/1800/1900 MHz) or four bands (850/900/1800/1900 MHz), and
are usually referred to as tri-band and quad-band phones, or world
phones; with such a phone one can travel internationally and use the
same handset.
• So if you want to buy gsm jammer,you should know that where do
you want to use and what frequencies can the jammer support.Only
then can you achieve your purpose.
• http://www.jammer-buy.com/gsm-jammer/c-26.html

8. • 4 bands cell phone jammer from:
• http://www.jammer-buy.com/gsm-jammer/p-6958.html