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20W Output Power Cell Phone Signal Jammer for Exam Halls , Up to 50m Long Distance

  • Shenzhen,China


  • SGS, ISO9001

  • GW-JB20

  • 1pcs

  • Negotiable

  • Carton with PE Foam

  • 3 Working Days After Received Payment

  • T/T, L/C, Western Union, MoneyGram

  • 5000pcs per Month


20W Output Power Cell Phone Signal Jammer for Exam Halls , Up to 50m Long Distance



Cell Phone Signal Jammer Description:


A mobile phone jammer is an instrument used to stop cellular phones from receiving signals from base stations. The jammer effectively disables cellular phones. It transmits on the same radio frequencies as the cell phone, disrupting the communication between the phone and the cell-phone base station in the tower. That's how the Signal Jammer working.


Now we recommend our GW-JB20 for you which can work excellently in jamming the signals at examination hall.

This is a desktop adjustable 20watt ouput power jammer, what is different from many other type of desktop adjustable output power jammers in the market is that it owns powerful jamming effect and ability. This is a 4 bands adjustable output power jammer so that it can cut off the 2G, 3G, 4G, WiFi Signals very easily, and since designed with high quality the jamming radius is up to 70 meters at most according to the signal strength.

The Signal Jammer GW-JB20 has 4 antennas supporting 4 frequencies of GSM, DCS, WCDMA, PCS or any other frequencies can be customized and it comes with good cooling system. 


GREETWIN COMPANY is a special manufacturer of signal jammers and signal repeaters.
Our market research and development department has introduced new products to meet the ever-changing needs of customers since 2008.
To solve your information security issues, is our relentless pursuit.

We also have a lot of high quality products on this website and will be grateful if you can browse more products.

Need mobility? Please browse our portable mobile blocker section.
As always, if you have any questions we are happy to assist you.


Cell Phone Signal Jammer Features:

1. Good cooling system,

2. Jamming range up to 50m.

3. cost-effective choice,

4. Stable capability, 

5. Output power 20w , make more efficient jamming.

6. Heat sink case makes the jammer work in a more stable and cool situation.

7. Four channels with different frequency range,

or customize other cellular standard in the world.

Such as Walkie Talkie,450MHz,GPRS,iDEN,GPS, Galileo,Compass,Glonass,UMTS,WiFi,AWS,LTE 4G.

8. Transmit noise signal to cut off all communication between cell phone and Base station.

The jammed cell phone will show “No Service” .

will not be able to receive or dial outgoing calls.


Cell Phone Signal Jammer Application:

Theatres, offices,Meeting Room, Oil and Gas Storage Facilities and fields, Hospitals,
Recording Studios, Banks, Contract Tendering Rooms, Churches, Conference
Rooms, Classrooms, Testing Facilities, Security Services, Military, Secret
Services, Libraries, Museums, Courts, Border Patrol and Drug Enforcement,

Customs, House, mosques,  Libraries, Prisons, etc.

Cell Phone Signal Jammer Specification:


Only interfere downlink frequency of mobile system, can’t affect normal operation of Base Station.


GW-JB20 is a sophisticated high power desktop cellular phone jammer.

It can be used for all the worldwide network frequency system. 

It is the best choice for Examination Hall, Conference rooms, and offices.


Output port


Average output power

Channel output power













or 3G




or 2110-2170MHz

Power supply: AC110-240V,DC 24V   Energy consumption: 60W

Dimension: 45*24*8.5cm       Running temperature: -10 to +55'C

External omni antennas       Weight: 3.5kg       Output power: 20w

Jamming range(radius): 20-50m (Depend on local signal intensity)          Humidity: 5% - 95%


20W Output Power Cell Phone Signal Jammer for Exam Halls , Up to 50m Long Distance 0




Add:  Baodeli industrial park, Longhua District, Shenzhen City, Guangdong Province, China   Tel: +86-15112267605
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