Editing ATM (section)

== Financial networks ==
{{more citations needed|section|date=June 2018}}<!--only last paragraph is cited-->
[[File:Geldautomaat.jpg|thumb|left|An ATM in the [[Netherlands]]. The [[logo]]s of a number of [[interbank network]]s to which it is connected are shown. The [[PIN (debit card)|PIN]] card logo is not displayed, although this system was in use here at the time.]]

Most ATMs are connected to [[interbank network]]s, enabling people to withdraw and deposit money from machines not belonging to the bank where they have their accounts or in the countries where their accounts are held (enabling cash withdrawals in local currency). Some examples of interbank networks include [[NYCE]], [[Pulse (interbank network)|PULSE]], [[Plus (interbank network)|PLUS]], [[Cirrus (interbank network)|Cirrus]], [[AFFN]], [[Interac]],<ref>{{cite web|url=http://www.interac.ca/en/interac-cash-consumer.html|title=Interac Cash web page|author=<!--Not stated-->|access-date=2 July 2018}}</ref> Interswitch, [[STAR (interbank network)|STAR]], [[LINK (UK)|LINK]], [[MegaLink]], and [[BancNet]].

ATMs rely on the authorization of a [[financial transaction]] by the card issuer or other authorizing institution on a 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 that operates the ATM; in other cases, they apply to all users.

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 utilises the vault or cash drawer within the merchant establishment, which allows for the use of a [[scrip cash dispenser]].

[[File:Diebold 1063 ATM with modem.jpg|thumb|upright|A [[Diebold 1063]]ix with a dial-up modem visible at the base]]

ATMs typically connect directly to their host or [[ATMC|ATM Controller]] on either [[ADSL]] or dial-up [[modem]] over a [[telephone]] line or directly on a leased line. Leased lines are preferable to [[plain old telephone service]] (POTS) lines because they require less time to establish a connection. Less-trafficked machines will usually rely on a dial-up modem on a POTS line rather than using a leased line, since a leased line may be comparatively more expensive to operate compared to a POTS line. 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 [[Systems Network Architecture|SNA]] over [[Synchronous Data Link Control|SDLC]], a [[Multidrop bus|multidrop protocol]] over [[Asynchronous communication|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 using methods such as [[Secure Sockets Layer|SSL]].<ref>{{Cite web|title=Eicon Networks Develops Ssl-vpn For Secure Remote Working|date=21 February 2005|url=http://www.ebcvg.com/press.php?id=794|access-date=2023-03-27|website=IT Observer 
| url-status= usurped 
|archive-url=https://web.archive.org/web/20070406205127/http://www.ebcvg.com/press.php?id=794|archive-date=6 April 2007}}</ref>