Dialer

A dialer (American English) or dialler (British English) is an electronic device or software that connects to a telephone line to monitor dialed numbers and automatically modify them for seamless access to services requiring long national or international access codes. It inserts or alters numbers based on the time of day, country, or area code, enabling users to connect through service providers offering the best rates. For example, it might use one provider for international calls and another for mobile networks. This technique is known as prefix insertion or least-cost routing. A line-powered dialer draws power directly from the telephone line, requiring no external source.

Another type of dialer is software that establishes an Internet or network connection over analog telephone lines or Integrated Services Digital Network (ISDN). Many operating systems include built-in dialers that use the Point-to-Point Protocol (PPP), such as WvDial.

Many internet service providers offer installation CDs to simplify the process of setting up a proper Internet connection. They either create an entry in the operating system's dialer or install a separate dialer (as the AOL software does).

In recent years, the term “dialer” has increasingly been associated with software that initiates calls or connections without the user’s informed consent regarding charges, often with the intent to defraud.

Call centers use various forms of automatic dialers to place outbound calls to people on contact lists.

Dialers are necessary to connect to the internet (at least for non-broadband connections), but some dialers are designed to connect to premium-rate numbers. The providers of such dialers often search for security vulnerabilities in the operating system installed on the user's computer and use them to set the computer up to dial up through their number, so as to make money from the calls.  Alternatively, some dialers inform the user about their purpose, with the promise of special content accessible only via the special number. Examples of this content include software for download, (usually illegal) trojans posing as MP3s, trojans posing as pornography, or 'underground' programs such as cracks and keygens.

The cost of setting up such a service is relatively low, amounting to a few thousand dollars for telecommunications equipment, whereupon the unscrupulous operator will typically take a significant percentage (up to 90%) of the cost of a premium rate call, with very few overheads of their own.

Users with DSLs (or similar broadband connections) are usually not affected. A dialer can be downloaded and installed, but dialing in is not possible as there are no regular phone numbers in the DSL network and users will not typically have their dial-up modem, if any, connected to a phone line. However, if an ISDN adapter or additional analog modem is installed, the dialer might still be able to initiate a connection.