The dial-up server uses an inbound connection, while the out dial-up client uses the outbound connection. Regarding installation procedures, the two will be exactly the same for most residences. As long as the telephone circuit can send and receive analog calls, it can act as either an inbound or outbound connection.
If there is a PBX involved, as there will be with most medium and large businesses, an analog circuit will need to be specifically provisioned for either inbound or outbound use. Inbound connections will require a dedicated phone number (and probably a dedicated analog circuit) while outbound-only connections can share an analog circuit with other outbound clients, providing there are enough analog circuits for each client that will simultaneously establish an outbound connection.
This was first published in January 2004