Recommendation I.210
describes the principles for defining telecommunication services supported by an
ISDN, including the concept of bearer services, bearer capabilities and
teleservices. It also provides the tools for the definition and description of
such services. The purpose of this
Recommendation is to define a recommended set of bearer service categories that
may be supported by an ISDN together with their overall provision. These
definitions form the basis for detailed descriptions of circuit mode bearer
services as given in Recommendation I.231 and packet-mode bearer services as
given in Recommendation I.232 and their associated bearer capabilities, which
are used to define the network capabilities required. Bearer services are fully described by prose
definitions and descriptions, by attributes and by dynamic descriptions, which
altogether define the service characteristics as they apply at a given
reference point where the customer accesses the service. Recommendation I.140
and Recommendation I.210, Annex B describe the use of attributes for this
purpose.