Pay-per-call

Pay-per-call (PPCall) was originally a billing system generally known as "900" calls (because most pay-per-call services used numbers in the 9xx range), where the phone company bills the caller a fee which is passed on to the owner of the number called. This service was predominantly used for billing phone sex services on a pay per minute basis.
In 2005 and with significant help from Google, an inverted web variant of PPCall was introduced, similar to online pay per click (PPC) advertising. With the web based PPCall service however, the call fee is charged to the merchant and paid to the web service provider for connecting the consumer to the advertised number. In 2010, functionality was extended for smart mobile phones so that the user could connect by clicking the phone number link, without having to dial the number manually.
Given the high rate of reported click fraud, Pay-per-call services is believed to be a better solution to connect potential customers to advertisers.
Pay Per Call System
A majority of original direct PPCall providers used web forms or optimized landing pages to help generate phone calls. On web based advertising platforms, merchants define their relevant key terms, choose desired categories and a geographic area for the ad to appear (local, regional or national). From there, they create their ad, containing their company name, address, a short description and a trackable toll-free telephone number of the PPCall provider, which redirects to the advertiser's actual phone number. This type of advertisement is popular with Yellow Pages companies.