w 0 Item(s) - £ 0.00£ 0.00
Next Day UK Delivery for Most Products Same Day Dispatch if Ordered by 3.30pm
Numerous Secure Payment Options Interest Free Credit Available
Fast Worldwide Shipping by DHL Discreet Packaging and Labelling
UK Support Team 02476 010 588 Easy to Understand Product Instructions

GSM Calculator Listening Device

Product Code C4LG

Made by Spy Equipment UK – Standard desktop calculator with inbuilt long term battery-powered GSM bug that is perfect for many applications. Ideal as a carry anywhere listening device, for inside the house, office, workshop or other indoor application. Very discreet and with excellent audio performance.

  • Shipping in 24 hours
  • Product out of stock
Ask A Question
Product Shipping

All parcels are discretely packaged and addressed with no mention of Spy Equipment UK or Spy branding. All parcels must be signed for and can't be left at a property without a signature. No shipping is required for Software/Subscription Products

UK Delivery Options
£2.75 - UK Standard (Up To 3 Working Days)
£6 - UK Standard (Up To 3 Working Days)
£7.50 - UK Special Delivery (Next Working Day - before 13.00 hours)
£26 - UK Express (Next Working Day - before 09.00 hours)
£16 - UK Saturday Delivery (before 13:00 hours)
Collected in-store
Europe Zone 1( Express )
£25 - Europe Zone (1 to 2 working days )
Europe Zone 2 ( Express )
£32 - Europe Zone 2 (1 to 3 working days )
Europe Zone 3 ( Express )
£38 - Europe Zone 3 (1 to 3 working days )
Worldwide Zone 1
£43 - Worldwide Zone 1 ( 2 - 4 working days )
Worldwide Zone 2
£48 - Worldwide Zone 2 ( 3 - 5 working days )
USA & Canada
£33 - USA & Canada ( 1 - 3 working days )
Product Code

£ 238.80 inc. VAT£ 199.00 ex. VAT

This product is currently out of stock, please fill in your email address below to be notified when it becomes available again

The GSM Calculator Listening Device is a discreet audio bug, built into a working calculator, that can provide the ability to listen ‘live’ to what is happening in the environment where it has been placed, without the need to have a permanent mains power supply.

Excellent Microphone – Auto-answering Listening Device

As with all GSM Bugs, the GSM Calculator Listening Bug requires a mobile phone SIM card inserted within so that it can be contacted from anywhere in the world, if required. When the number of the inserted SIM is called, the device will – without alerting attention in any way – auto-answer the call and open up its in-built sensitive microphone. The microphone will enable the caller to listen into the surroundings within a radius of up to ten metres. This amazing GSM listening bug unit delivers really clear audio quality and because it is enclosed inside a working desktop calculator, it can be left in plain sight or even used in a meeting situation, if desired, without arousing suspicion.

A Listening Bug With A Decent Battery Performance

The major limiting factor with most small stand-alone spy devices is the battery life. The GSM Calculator listening device is certainly quite compact, but still manages to function as a GSM audio bug for a perfectly acceptable period of time, given the size of the product. The internal lithium ion rechargeable battery pack will give a combination of up to 9 days standby time and up to 9 hours of listening-in time (optimum conditions), meaning that you will get a combination of the two figures dependant on how often you call in and for how long.

A GSM Listening Bug Made For Variety Of Situations

The unit is best deployed in a position where it can pick up sounds in the environment where it has been placed. At home, it could be left in plain sight – maybe on a desk, or out of view on top of a cupboard – if required. The device does not require credit on the SIM card to receive the call, however it is worth noting that if using a Pay-as-you-go SIM then after a period of time the SIM supplier may cut off the SIM card from the network because with no outgoing calls or transactions undertaken by the SIM the network is unable to charge for its use for incoming calls only. Changing for a fresh Prepay SIM every few months generally gets around this issue. Alternatively you could use a low cost contract SIM to ensure that the network stays active.

Rechargeable Internal Battery

The internal lithium battery in this GSM listening device can be recharged using the supplied magnetic USB lead for subsequent stand-alone deployment. Charge time is up to four hours and can be done by connecting to a computer USB port or for best results by using the Mains USB plug, which normally results in a faster charge time. Contact us if you would like to know more about this listening device and to discuss whether this particular product is right for you.


Interested in learning more about this device? Discover our article Hear About Our New Listening Device – The GSM Calculator.

  • Battery powered GSM listening device built into an everyday working desktop calculator
  • Call this device from any mobile phone or landline – unit will auto-answer
  • Outstandingly crisp audio quality – microphone has adjustable sensitivity that can even be controlled remotely (by coded SMS message)
  • Totally discreet operation – this listening device auto answers without any alerts (lights or noise)
  • Discreet pin operated on/off switch – Requires opening to recharge internal battery
  • Simple to use ‘plug and go’ technology – No specialist technical knowledge required
  • Internal Lithium Ion rechargeable battery (550mAh) – charge from computer USB or mains power adapter
  • Up to 9 days standby time – Up to 9 hours listening-in time (battery life maximises after 3 to 4 full charge/discharges)
  • Quad-band operation – accepts any GSM network SIM (850, 900, 1800 or 1900MHz) covering all countries worldwide
  • This listening bug is designed to work with any activated micro SIM card – EE SIM supplied
  • Calculator unit dimensions: 145 mm x 103 mm x 28 mm high (from desktop surface to highest point)
  • Includes magnetic USB charging lead and USB to mains power adapter and a full set of instructions
  • Perfect standalone listening bug suited for deployment in the home in the office or any other room environment

Would the GSM Calculator Listening Device still pick up sounds if it was on top of a cupboard or underneath a low settee?

As long as the device is in the airspace of the environment where conversation is taking place and the microphone holes are not covered, then it will pick up on these voices (within the sensitivity range)

If the battery expires during use, will the bugging device make any sounds to indicate that the battery is about to go?

The unit is totally covert. The unit will give no visual or audible indication of the battery’s expiration.

Will this GSM listening device work outside the UK?

This unit has a quad-band modem and therefore will work anywhere around the world on the GSM networks 850, 900, 1800 and 1900MHz bands.

Will this unit take any GSM SIM card?

These units have been designed to accept a micro size SIM cards from any network, although of course it has been impossible to test every network SIM provider around the world and these are designed for the 2G network so in the UK 3 Network SIM’s cannot be used. Also in USA the 3G network is no longer active.

If I left this on a desk, would it be obvious what it was?

The device is not a giveaway, although a detailed examination by somebody with knowledge of surveillance devices may arouse some suspicion because of small holes in the sides for microphone and pin on/off switch. To the untrained eye the GSM Calculator should not alert attention.

Can I call the unit from any phone (mobile or landline phone)?

Yes, the unit will accept calls from both types, but to make use of the voice activation facility only a mobile phone can be used.

Consider the Following When Using this Listening Bug:

  • You will need a working mobile phone to enable you to listen in to the bug and control its features.
  • The device does not require credit on the SIM card to receive the call, however it is worth noting that if using a Pay-as-you-go SIM then after a period of time the SIM supplier may cut off the SIM card from the network. This is something that is solely under control of the network provider and not Spy Equipment UK.
  • The calculator listening bug is powered separately from the GSM unit which means the calculator function will still work even if the listening device battery needs charge.
  • Just like any mobile phone, the device can lose network signal from time to time, especially when deployed inside a moving vehicle that is travelling through varying signal strength areas.