With two-level bidirectional supply chains, the initial service provider is an interface between the service customer and the service supplier. That initial service provider functionsas a value-adding go-between inthe process.
There is a third type of service supply chains that is not bidirectional, but incorporates the customer-supplier duality. This is a class of service processes in which the customer provides inputs to the service provider, who processes the inputs and delivers them to an entity which is different from the customer. Even if the original customers never see the original delivered output, they do receive benefits fromthe delivery.
An example is postal or package delivery, where customers deliver their documents or packages to the delivery service provider to be spatially transformed (i.e. moved) to a desired location. The item being delivered might be informational, such as a voice being processed by a telephone company. Another example is broadcasttelevisionwherecustomers,theadvertisers,providetheiradvertisements as input to the production process. Broadcasters package the advertisements with television programming and deliver it to the viewers. The advertisers who provide the input may never personally see the advertisements but will still receive the benefitofincreasedproductawarenessinviewers.