Allow your subscribers to benefit from lower-cost calls subsidised through advertisements.
When making a call, an advertisement is played to the subscriber. In return, the subscriber pays less for the call, with the 3rd party advertiser paying the subsidy.
Typically an advert is played to the calling party before call set-up continues.
Additional adverts may be played during the call to further subsidise on-going call charges. These may be played to the calling and called parties, or just played to the calling party with the other party receiving an "on-hold" announcement (or other suitable audio).
This service may be permanently tied to a particular tariff. Alternatively, the subscriber (on any one of a number of tariffs) may be given control to turn the service on and off.
Benefits for the Network Operator: