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Automated teller machine

Related subjects Engineering

An NCR Personas 75-Series interior, multi-function ATM in the USA
An NCR Personas 75-Series interior, multi-function ATM in the USA
Smaller indoor ATMs dispense money inside convenience stores and other busy areas, such as this off-premise Wincor Nixdorf mono-function ATM in Sweden.
Smaller indoor ATMs dispense money inside convenience stores and other busy areas, such as this off-premise Wincor Nixdorf mono-function ATM in Sweden.

An automated teller machine (ATM) is a computerized telecommunications device that provides the customers of a financial institution with access to financial transactions in a public space without the need for a human clerk or bank teller. On most modern ATMs, the customer is identified by inserting a plastic ATM card with a magnetic stripe or a plastic smartcard with a chip, that contains a unique card number and some security information, such as an expiration date or CVC (CVV). Security is provided by the customer entering a personal identification number (PIN).

Using an ATM, customers can access their bank accounts in order to make cash withdrawals (or credit card cash advances) and check their account balances. ATMs are known by various casual terms including automated banking machine, money machine, cash machine, hole-in-the-wall, cashpoint or Bancomat (in Europe and Russia).


An old Nixdorf ATM
An old Nixdorf ATM

A mechanical cash dispenser was developed and built by Luther George Simjian and installed in 1939 in New York City by the City Bank of New York, but removed after 6 months due to the lack of customer acceptance.

The ATM got smaller, faster and easier over the years. Thereafter, the history of ATMs paused for over 25 years, until De La Rue developed the first electronic ATM, which was installed first in Enfield Town in North London on 27 June 1967 by Barclays Bank.. This instance of the invention is credited to John Shepherd-Barron, although various other engineers were awarded patents for related technologies at the time. Shepherd-Barron was awarded an OBE in the 2005 New Year's Honours List. The first person to use the machine was Reg Varney of " On the Buses" fame, a British Television programme from the 1960s. The first ATMs accepted only a single-use token or voucher, which was retained by the machine. These worked on various principles including radiation and low-coercivity magnetism that was wiped by the card reader to make fraud more difficult. The idea of a PIN stored on the card was developed by the British engineer John Rose in 1965.

However, the modern, networked ATM was invented in Dallas, Texas, by Don Wetzel in 1968. Wetzel was a department head at an automated baggage-handling company called Docutel. In 1995 the Smithsonian's National Museum of American History recognized Docutel and Wetzel as the inventors of the ATM.

ATMs first came into wide UK use in 1973; the IBM 2984 was designed at the request of Lloyds Bank. The 2984 CIT (Cash Issuing Terminal) was the first true Cashpoint, similar in function to today's machines; Cashpoint is still a registered trademark of Lloyds TSB in the U.K. All were online and issued a variable amount which was immediately deducted from the account. A small number of 2984s were supplied to a USA bank. Notable historical models of ATMs include the IBM 3624 and 473x series, Diebold 10xx and TABS 9000 series, and NCR 5xxx series.


An ATM Encrypting PIN Pad (EPP) with German markings
An ATM Encrypting PIN Pad (EPP) with German markings

ATMs are placed not only near or inside the premises of banks, but also in locations such as shopping centers/malls, airports, grocery stores, petrol/gas stations, restaurants, or any place large numbers of people may gather. These represent two types of ATM installations: on and off premise. On premise ATMs are typically more advanced, multi-function machines that complement an actual bank branch's capabilities and thus more expensive. Off premise machines are deployed by financial institutions and also ISOs (or Independent Sales Organizations) where there is usually just a straight need for cash, so they typically are the cheaper mono-function devices. In Canada, when an ATM is not operated by a financial institution it is known as a "White Label ATM".

In North America, banks often have drive-through lanes providing access to ATMs.

Many ATMs have a sign above them indicating the name of the bank or organization owning the ATM, and possibly including the list of ATM networks to which that machine is connected. This type of sign is called a topper.

Financial networks

An ATM in the Netherlands.  The logos of a number of interbank networks this ATM is connected to are shown.
An ATM in the Netherlands. The logos of a number of interbank networks this ATM is connected to are shown.

Most ATMs are connected to interbank networks, enabling people to withdraw and deposit money from machines not belonging to the bank where they have their account or in the country where their accounts are held (enabling cash withdrawals in local currency). Some examples of interbank networks include PLUS, Cirrus, Interac and LINK.

ATMs rely on authorization of a financial transaction by the card issuer or other authorizing institution via the communications network. This is often performed through an ISO 8583 messaging system.

Many banks charge ATM usage fees. In some cases, these fees are charged solely to users who are not customers of the bank where the ATM is installed; in other cases, they apply to all users. Many people oppose these fees because ATMs are actually less costly for banks than withdrawals from human tellers.

In order to allow a more diverse range of devices to attach to their networks, some interbank networks have passed rules expanding the definition of an ATM to be a terminal that either has the vault within its footprint or utilizes the vault or cash drawer within the merchant establishment, which allows for the use of a scrip cash dispenser.

A Diebold 1063ix with a dial-up modem visible at the base
A Diebold 1063ix with a dial-up modem visible at the base

ATMs typically connect directly to their ATM Transaction Processor via either a dial-up modem over a telephone line or directly via a leased line. Leased lines are preferable to POTS lines because they require less time to establish a connection. Leased lines may be comparatively expensive to operate versus a POTS line, meaning less-trafficked machines will usually rely on a dial-up modem. That dilemma may be solved as high-speed Internet VPN connections become more ubiquitous. Common lower-level layer communication protocols used by ATMs to communicate back to the Bank include SNA over SDLC, TC500 over Async, X.25, and TCP/IP over Ethernet.

In addition to methods employed for transaction security and secrecy, all communications traffic between the ATM and the Transaction Processor may also be encrypted via methods such as SSL.

Global use

An ATM in the Tokyo subway
An ATM in the Tokyo subway

There are no hard international or government-compiled numbers totaling the complete number of ATMs in use worldwide. Estimates developed by ATMIA place the number of ATMs in use at over 1.5 million as of August 2006.

For the purpose of analyzing ATM usage around the world, financial institutions generally divide the world into seven regions, due to the penetration rates, usage statistics, and features deployed. Four regions (USA, Canada, Europe, and Japan) have high numbers of ATMs per million people and generally slowing growth rates. Despite the large number of ATMs, there is additional demand for machines in the Asia/Pacific area as well as in Latin America. ATMs have yet to reach high numbers in the Near East/Africa.

The world's most northerly installed ATM is located at Longyearbyen, Svalbard, Norway.

The world's most southerly installed ATM is located at McMurdo Station, Antarctica.

While ATMs are ubiquitous on modern cruise ships, ATMs can also be found on some US Navy ships.

In the United Kingdom, an ATM may be colloqually referred to as a "Cashpoint", named after the Lloyds Bank ATM brand, or hole-in-the-wall.


A block diagram of an ATM.
A block diagram of an ATM.

An ATM is typically made up of the following devices:

  • CPU (to control the user interface and transaction devices)
  • Magnetic and/or Chip card reader (to identify the customer)
  • PIN Pad (similar in layout to a Touch tone or Calculator keypad), often manufactured as part of a secure enclosure.
  • Secure cryptoprocessor, generally within a secure enclosure.
  • Display (used by the customer for performing the transaction)
  • Function key buttons (usually close to the display) or a Touchscreen (used to select the various aspects of the transaction)
  • Record Printer (to provide the customer with a record of their transaction)
  • Vault (to store the parts of the machinery requiring restricted access)
  • Housing (for aesthetics and to attach signage to)

Recently, due to heavier computing demands and the falling price of computer-like architectures, ATMs have moved away from custom hardware architectures using microcontrollers and/or application-specific integrated circuits to adopting a hardware architecture that is very similar to a personal computer. Many ATMs are now able to use operating systems such as Microsoft Windows and Linux. Although it is undoubtedly cheaper to use commercial off-the-shelf hardware, it does make ATMs vulnerable to the same sort of problems exhibited by conventional computers.


Interior of an NCR Personas 70 freestanding ATM, during servicing
Interior of an NCR Personas 70 freestanding ATM, during servicing

The vault of an ATM is within the footprint of the device itself and is where items of value are kept. Scrip cash dispensers do not incorporate a vault.

Mechanisms found inside the vault may include:

  • Dispensing mechanism (to provide cash or other items of value)
  • Deposit mechanism, including a Cheque Processing Module and Batch Note Acceptor (to allow the customer to make deposits)
  • Security sensors (Magnetic, Thermal, Seismic)
  • Locks: (to ensure controlled access to the contents of the vault)

ATM vaults are supplied by manufacturers in several grades. Factors influencing vault grade selection include cost, weight, regulatory requirements, ATM type, operator risk avoidance practices, and internal volume requirements.

Industry standard vault configurations include Underwriters Laboratories UL-291 "Business Hours" and Level 1 Safes, RAL 626/3, TL-30 derivatives, and CEN EN 1143-1:2005 - CEN III/VdS and CEN IV/LGAI/VdS.

ATM manufacturers recommend that vaults be attached to the floor to prevent theft.


A Wincor Nixdorf ATM running Windows 2000
A Wincor Nixdorf ATM running Windows 2000

With the migration to commodity PC hardware, standard commercial "off-the-shelf" operating systems and programming environments can be used inside of ATMs. Typical platforms used in ATM development include RMX, OS/2, and Microsoft operating systems (such as MS-DOS, PC-DOS, Windows NT, Windows 2000, Windows XP Professional, or Windows XP Embedded). Java, Linux and Unix may also be used in these environments.

Linux is also finding some reception in the ATM marketplace. An example of this is Banrisul, the largest bank in the south of Brazil, which has replaced the MS-DOS operating systems in its ATMs with Linux. Banco do Brasil is also migrating ATMs to Linux.

Common application layer transaction protocols, such as Diebold 911 or 912, IBM PBM, and NCR NDC or NDC+ provide emulation of older generations of hardware on newer platforms with incremental extensions made over time to address new capabilities. Most major ATM manufacturers provide software packages that implement these protocols. Newer protocols such as IFX have yet to find wide acceptance by transaction processors.

With the move to a more standardized software base, financial institutions have been increasingly interested in the ability to pick and choose the application programs that drive their equipment. WOSA/XFS, now known as CEN XFS (or simply XFS), provides a common API for accessing and manipulating the various devices of an ATM.

J/XFS is a Java implementation of the CEN XFS API.

While the perceived benefit of XFS is similar to the Java's "Write once, run anywhere" mantra, often different ATM hardware vendors have different interpretations of the XFS standard. The result of these differences in interpretation means that ATM applications typically use a middleware to even out the differences between various platforms.

Notable XFS middleware platforms include Triton PRISM, Diebold Agilis, CR2 BankWorld, KAL Kalignite, NCR Corporation Aptra Edge, Phoenix Interactive VISTAatm, and Wincor Nixdorf Protopas.

With the move of ATMs to industry-standard computing environments, concern has risen about the integrity of the ATM's software stack.


An ATM with card reader and PIN keypad.
An ATM with card reader and PIN keypad.

Security, as it relates to ATMs, has several dimensions. ATMs also provide a practical demonstration of a number of security systems and concepts operating together and how various security concerns are dealt with.


This is a Wincor Nixdorf Procash 2100xe Frontload that was opened with an angle grinder.
This is a Wincor Nixdorf Procash 2100xe Frontload that was opened with an angle grinder.

Early ATM security focused on making the ATMs invulnerable to physical attack; they were effectively safes with dispenser mechanisms. A number of attacks on ATMs resulted, with thieves attempting to steal entire ATMs by ram-raiding. Since late 1990s, criminal groups operating in Japan improved ram-raiding by stealing and using a truck loaded with a heavy construction machinery to effectively demolish or uproot an entire ATM and any housing to steal its cash.

Another attack method is to seal all openings of the ATM with silicone and fill the vault with a combustible gas or to place an explosive inside, attached, or near the ATM. This gas or explosive is ignited and the vault is opened or distorted by the force of the resulting explosion and the criminals can break in.

Modern ATM physical security, per other modern money-handling security, concentrates on denying the use of the money inside the machine to a thief, by means of techniques such as dye markers and smoke canisters.

Transactional secrecy and integrity

The security of ATM transactions relies mostly on the integrity of the secure cryptoprocessor: the ATM often uses commodity components that are not considered to be " trusted systems".

Encryption of personal information, required by law in many jurisdictions, is used to prevent fraud. Sensitive data in ATM transactions are usually encrypted with DES, but transaction processors now usually require the use of Triple DES. Remote Key Loading techniques may be used to ensure the secrecy of the initialization of the encryption keys in the ATM. Message Authentication Code (MAC) or Partial MAC may also be used to ensure messages have not been tampered with while in transit between the ATM and the financial network.

Customer identity integrity

A BTMU ATM with a palm scanner (to the right of the screen)
A BTMU ATM with a palm scanner (to the right of the screen)

There have also been a number of incidents of fraud where criminals have attached fake keypads or card readers to existing machines. These have then been used to record customers' PINs and bank card information in order to gain unauthorised access to their accounts. Various ATM manufacturers have put in place countermeasures to protect the equipment they manufacture from these threats.

Alternate methods to verify cardholder identities have been tested and deployed in some countries, such as finger and palm vein patterns, iris, and facial recognition technologies. Cost of integrating and implementing these technologies along with concerns about consumer acceptance have limited their deployment so far.

Device operation integrity

ATMs that are exposed to the outside must be vandal and weather resistant.
ATMs that are exposed to the outside must be vandal and weather resistant.

Openings on the customer-side of ATMs are often covered by mechanical shutters to prevent tampering with the mechanisms when they are not in use. Alarm sensors are placed inside the ATM and in ATM servicing areas to alert their operators when doors have been opened by unauthorized personnel.

Rules are usually set by the government or ATM operating body that dictate what happens when integrity systems fail. Depending on the jurisdiction, a bank may or may not be liable when an attempt is made to dispense a customer's money from an ATM and the money either gets outside of the ATM's vault, or was exposed in a non-secure fashion, or they are unable to determine the state of the money after a failed transaction. Bank customers often complain that banks have made it difficult to recover money lost in this way, but this is often complicated by the Bank's own internal policies regarding suspicious activities typical of the criminal element.

Customer security

Security guards watching over ATMs that have been installed in a van.
Security guards watching over ATMs that have been installed in a van.

In some areas, multiple security cameras and security guards are a common feature. The NY State Comptroller's Office has criticized the NY State Department of Banking for not following through on safety inspections of ATMs in high crime areas. http://www.osc.state.ny.us/press/releases/oct07/100407.htm

Critics of ATM operators assert that the issue of customer security appears to have been abandoned by the banking industry; it has been suggested that efforts are now more concentrated on deterrent legislation than on solving the problem of forced withdrawals.

At least as far back as July 30, 1986, critics of the industry have called for the adoption of an emergency PIN system for ATMs, where the user is able to send a silent alarm in response to a threat. Legislative efforts to require an emergency PIN system have appeared in Illinois, Kansas and Georgia, but none have succeeded as of yet.

The lack of hard statistics about violent ATM crime makes it difficult to make an objective determination about how much effort should be made regarding detterent methods such as cameras, landscaping, emergency PINs, etc. However, these statistics are, in fact, quite easy to obtain. Normally, the crime statistician will use either the felony code section as an index number or the new National Incident Based Reporting System codes to track crime patterns, (NIBRS). However if the police agency has a master list of ATMs in the community, then all that the analyst needs to do is overlay that list of addresses against robberies, attempted robberies, abductions, home invasions, carjackings, rapes and murders and all incidents connected to an ATM address will be pulled up by the computer.

Alternative uses

Two NCR Personas 84 ATMs at a bank in Jersey dispensing two types of pound sterling banknotes: Bank of England notes, and States of Jersey notes.
Two NCR Personas 84 ATMs at a bank in Jersey dispensing two types of pound sterling banknotes: Bank of England notes, and States of Jersey notes.

Although ATMs were originally developed as just cash dispensers, they have evolved to include many other bank-related functions. In some countries, especially those which benefit from a fully integrated cross-bank ATM network (e.g.: Multibanco in Portugal), ATMs include many functions which are not directly related to the management of one's own bank account, such as:

Increasingly Banks are seeking to use the ATM as a sales device to deliver pre approved loans and targeted advertising using products such as ITM (the Intelligent Teller Machine) from CR2 or Aptra Relate from NCR.

In Canada, ATMs are called guichets automatiques in French and sometimes "Bank Machines" in English. The Interac shared cash network does not allow for the selling of goods from ATMs due to specific security requirements for PIN entry when buying goods.

ATMs can also act as an advertising channel for companies to advertise their own products or third-party products and services.

A South Korean ATM with mobile bank port and bar code reader.
A South Korean ATM with mobile bank port and bar code reader.

Manufactures have demonstrated and have deployed several different technologies on ATMs that have not yet reached worldwide acceptance, such as:

  • Biometrics, where authorization of transactions is based on the scanning of a customer's fingerprint, iris, face, etc. Biometrics on ATMs can be found in Asia.
  • Cheque/Cash Acceptance, where the ATM accepts and recognise cheques and/or currency without using envelopes Expected to grow in importance in the US through Check 21 legislation.
  • Bar code scanning
  • On-demand printing of "items of value" (such as movie tickets, Travellers Cheques, etc.)
  • Dispensing additional media (such as phone cards)
  • Co-ordination of ATMs with mobile phones
  • Customer-specific advertising
  • Integration with non-banking equipment


An ATM running Microsoft Windows that has crashed.
An ATM running Microsoft Windows that has crashed.

Before an ATM is placed in a public place, it typically has undergone extensive testing with both test money and the backend computer systems that allow it to perform transactions. Banking customers also have come to expect high reliability in their ATMs, which provides incentives to ATM providers to minimize machine and network failures. Financial consequences of incorrect machine operation also provide high degrees of incentive to minimize malfunctions.

ATMs and the supporting electronic financial networks are generally very reliable, with industry benchmarks typically producing 98.25% customer availability for ATMs and up to 99.999% availability for host systems. If ATMs do go out of service, customers could be left without the ability to make transactions until the beginning of their bank's next time of opening hours.

Of course, not all errors are to the detriment of customers; there have been cases of machines giving out money without debiting the account, or giving out higher value notes as a result of incorrect denomination of banknote being loaded in the money cassettes. Errors that can occur may be mechanical (such as card transport mechanisms; keypads; hard disk failures); software (such as operating system; device driver; application); communications; or purely down to operator error.

An ATM running OS/2 that has crashed.
An ATM running OS/2 that has crashed.

To aid in reliability, some ATMs print each transaction to a roll paper journal that is stored inside the ATM, which allows both the users of the ATMs and the related financial institutions to settle things based on the records in the journal in case there is a dispute. In some cases, transactions are posted to an electronic journal to remove the cost of supplying journal paper to the ATM and for more convenient searching of data.

Improper money checking can cause the possibility of a customer receiving counterfeit banknotes from an ATM. While Bank personnel are generally trained better at spotting and removing counterfeit cash, the resulting ATM money supplies used by banks provide no absolute guarantee for proper banknotes, as the Federal Criminal Police Office of Germany has confirmed that there are regularly incidents of false banknotes having been provided through bank ATMs. Some ATMs may be stocked and wholly owned by outside companies, which can further complicate this problem when it happens. Bill validation technology can be used by ATM providers to help ensure the authenticity of the cash before it is stocked in an ATM; ATMs that have cash recycling capabilities include this capability.


As with any device containing objects of value, ATMs and the systems they depend on to function are the targets of fraud. Fraud against ATMs and people's attempts to use them takes several forms.

The first known instance of a fake ATM was installed at a shopping mall in Manchester, Connecticut in 1993. By modifying the inner workings of a Fujitsu model 7020 ATM, a criminal gang known as The Bucklands Boys were able to steal information from cards inserted into the machine by customers.

In some cases, bank fraud could occur at ATMs whereby the bank accidentally stocks the ATM with bills in the wrong denomination, therefore giving the customer more money than should be dispensed. The result of receiving too much money may be influenced on the Card Holder Agreement in place between the customer and the Bank.

In a variation of this, WAVY-TV reported an incident in Virginia Beach of September 2006 where a hacker who had probably obtained a factory-default admin password for a gas station's white label ATM caused the unit to assume it was loaded with $5 USD bills instead of $20s, enabling himself--and many subsequent customers--to walk away with four times the money they said they wanted to withdraw.

ATM behaviour can change during what is called "stand-in" time, where the Bank's cash dispensing network is unable to access databases that contain account information (possibly for database maintenance). In order to give customers access to cash, customers may be allowed to withdraw cash up to a certain amount that may be less than their usual daily withdrawal limit, but may still exceed the amount of available money in their account, which could result in fraud.

Card fraud

In an attempt to prevent criminals from shoulder surfing the customer's PINs, some banks draw privacy areas on the floor.
In an attempt to prevent criminals from shoulder surfing the customer's PINs, some banks draw privacy areas on the floor.

For a low-tech form of fraud, the simplest is to simply steal a customer's card. A later variant of this approach is to trap the card inside of the ATM's card reader with a device often referred to as a Lebanese loop. When the customer gets frustrated by not getting the card back and walks away from the machine, the criminal is able to remove the card and withdraw cash from the customer's account.

Another simple form of fraud involves attempting to get the customer's bank to issue a new card and stealing it from their mail.

Some ATMs may put up warning messages to customers to not use them when it detects possible tampering.
Some ATMs may put up warning messages to customers to not use them when it detects possible tampering.

The concept and various methods of copying the contents of an ATM card's magnetic stripe on to a duplicate card to access other people's financial information was well known in the hacking communities by late 1990.

In 1996 Andrew Stone, a computer security consultant from Hampshire in the UK was convicted of stealing in excess of £1 million Sterling (at the time equivalent to US$1.6 million) by pointing high definition video cameras at ATMs from a considerable distance, and by recording the card numbers, expiry dates, etc. from the embossed detail on the ATM cards along with video footage of the PINs being entered. After getting all the information from the videotapes, he was able to produce clone cards which not only allowed him to withdraw the full daily limit for each account, but also allowed him to sidestep withdrawal limits by using multiple copied cards. In court, it was shown that he could withdraw as much as £10,000 per hour by using this method. Stone was sentenced to five years and six months in prison.

By contrast, a newer high-tech modus operandi involves the installation of a magnetic card reader over the real ATM's card slot and the use of a wireless surveillance camera or a modified digital camera to observe the user's PIN. Card data is then cloned onto a second card and the criminal attempts a standard cash withdrawal. The availability of low-cost commodity wireless cameras and card readers has made it a relatively simple form of fraud, with comparatively low risk to the fraudsters.

In an attempt to stop these practices, countermeasures against card cloning have been developed by the banking industry, in particular by the use of smart cards which cannot easily be copied or spoofed by un-authenticated devices, and by attempting to make the outside of their ATMs tamper evident. Older chip-card security systems include the French Carte Bleue, Visa Cash, Mondex, Blue from American Express and EMV '96 or EMV 3.11. The most actively developed form of smart card security in the industry today is known as EMV 2000 or EMV 4.x.

EMV is widely used in the UK ( Chip and PIN) and parts of Europe, but when it is not available in a specific area, ATMs must fallback to using the easy to copy magnetic stripe to perform transactions. This fallback behaviour can be exploited.

Related devices

A Talking ATM is a type of ATM that provides audible instructions so that persons who cannot read an ATM screen can independently use the machine. All audible information is delivered privately through a standard headphone jack on the face of the machine. Information is delivered to the customer either through pre-recorded sound files or via text-to-speech speech synthesis.

A postal interactive kiosk may also share many of the same components as an ATM (including a vault), but only dispenses items relating to postage.

A scrip cash dispenser may share many of the same components as an ATM, but lacks the ability to dispense physical cash and consequently requires no vault. Instead, the customer requests a withdrawal transaction from the machine, which prints a receipt. The customer then takes this receipt to a nearby sales clerk, who then exchanges it for cash from the till.

A Teller Assist Unit may also share many of the same components as an ATM (including a vault), but they are distinct in that they are designed to be operated solely by trained personnel and not the general public, they do not integrate directly into interbank networks, and are usually controlled by a computer that is not directly integrated into the overall construction of the unit.

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