6. Services

6.1 Service classification

Telecommunications services are the possibilities made available to users of a telecommunications network.

ISDN offers a range of functional capabilities that enable users connected to it to benefit from a series of telecommunications services:

• support services ;

• teleservices ;

• additional services.

Support services and teleservices are offered on their own as basic services, while additional services must accompany one of the previous two (figure 3 ).