The ISDN command message protocol

``Messages'' (sometimes called ``commands'') convey information between applications and ISDN drivers. An ISDN message is sent in an M_PROTO(D7str) type STREAMS message as a primitive described in Section D7isdn manual pages. The control portion contains a isdn_msg_hdr(D4isdn) header; message parameters are coded in the control portion following the isdn_msg_hdr.

SCO ISDN command message

ISDN messages are always followed by corresponding answering messages. So, the application sends a request (_REQ) to an ISDN driver, and the driver answers with a confirmation (_CONF). Similarly, the ISDN driver sends an indication (_IND) message to an application, and the application answers with a response (_RESP) indication.

Messages contain information about these services:

CONNECT

call setup

DISCONNECT

call teardown

ALERT

compatibility to call

INFO

signalling information

DATA

data transmission

RESET

reset of logical transmission

FACILITY

additional facilities, such as extension equipment

LISTEN

enable call indication

MANUFACTURER

vendor-specific operation

SELECT_B_PROTOCOL

change current protocol stack of a logical connection

There are three logical types of messages, shown in the following tables:

• signalling protocols, concerning the signalling protocol of the ISDN D-channel

• logical connections, concerning logical connections on the B- or D-channels

• administrative and other services

Signaling protocol primitives

Service	Primitives
CONNECT	ISDN_CONNECT.ISDN_REQ(D7isdn) ISDN_CONNECT.ISDN_CONF(D7isdn) ISDN_CONNECT.ISDN_IND(D7isdn) ISDN_CONNECT.ISDN_RESP(D7isdn)
CONNECT	ISDN_CONNECT_ACTIVE.ISDN_IND(D7isdn) ISDN_CONNECT_ACTIVE.ISDN_RESP(D7isdn)
DISCONNECT	ISDN_DISCONNECT.ISDN_REQ(D7isdn) ISDN_DISCONNECT.ISDN_CONF(D7isdn) ISDN_DISCONNECT.ISDN_IND(D7isdn) ISDN_DISCONNECT.ISDN_RESP(D7isdn)
ALERT	ISDN_ALERT.ISDN_REQ(D7isdn) ISDN_ALERT.ISDN_CONF(D7isdn)
INFO	ISDN_INFO.ISDN_REQ(D7isdn) ISDN_INFO.ISDN_CONF(D7isdn) ISDN_INFO.ISDN_IND(D7isdn) ISDN_INFO.ISDN_RESP(D7isdn)

Logical connection primitives

Service	Primitives
CONNECT	ISDN_CONNECT_B3.ISDN_REQ(D7isdn) ISDN_CONNECT_B3.ISDN_CONF(D7isdn) ISDN_CONNECT_B3.ISDN_IND(D7isdn) ISDN_CONNECT_B3.ISDN_RESP(D7isdn)
CONNECT	ISDN_CONNECT_B3_ACTIVE.ISDN_IND(D7isdn) ISDN_CONNECT_B3_ACTIVE.ISDN_RESP(D7isdn)
CONNECT	ISDN_CONNECT_B3_T90_ACTIVE.ISDN_IND(D7isdn) ISDN_CONNECT_B3_T90_ACTIVE.ISDN_RESP(D7isdn)
DISCONNECT	ISDN_DISCONNECT_B3.ISDN_REQ(D7isdn) ISDN_DISCONNECT_B3.ISDN_CONF(D7isdn) ISDN_DISCONNECT_B3.ISDN_IND(D7isdn) ISDN_DISCONNECT_B3.ISDN_RESP(D7isdn)
DATA	ISDN_DATA_B3.ISDN_CONF(D7isdn) ISDN_DATA_B3.ISDN_IND(D7isdn) ISDN_DATA_B3.ISDN_REQ(D7isdn) ISDN_DATA_B3.ISDN_RESP(D7isdn)
RESET	ISDN_RESET_B3.ISDN_CONF(D7isdn) ISDN_RESET_B3.ISDN_IND(D7isdn) ISDN_RESET_B3.ISDN_REQ(D7isdn) ISDN_RESET_B3.ISDN_RESP(D7isdn)

Administrative primitives

Service	Primitives
FACILITY	ISDN_FACILITY.ISDN_CONF(D7isdn) ISDN_FACILITY.ISDN_IND(D7isdn) ISDN_FACILITY.ISDN_REQ(D7isdn) ISDN_FACILITY.ISDN_RESP(D7isdn)
LISTEN	ISDN_LISTEN.ISDN_CONF(D7isdn) ISDN_LISTEN.ISDN_REQ(D7isdn)
MANUFACTURER	ISDN_MANUFACTURER(D7isdn)
SELECT_B_PROTOCOL	ISDN_SELECT_B_PROTOCOL.ISDN_CONF(D7isdn) ISDN_SELECT_B_PROTOCOL.ISDN_REQ(D7isdn)