The service allows you finding out who has called you, when the telephone line was busy, switched off or was outside the zone of coverage. By doing so, it ensures that an important call will not be missed.
According to the American Marketing Association, - "Marketing
is the activity, set of institutions, and processes for creating,
communicating, delivering, and exchanging offerings that have value for
customers, clients, partners, and society at large." A company, which
provides marketing services, should be capable of doing all the above listed.