AT&T AT&T manual Connecting Configurations, Controlling Features

Setup mode is entered.

f. Data Call Setup Mode

Data Call Setup Mode is a transitional state entered after Transfer To Data, Data Terminal Dialing, or during auto-answer; it exists during the handshake between data ports.

If the endpoints are compatible and handshaking is successful, a data connection is established. If handshake failure occurs, the user is notified and the data endpoint returns to the Idle mode. Successful handshake must occur within 15 seconds of answer at the called data endpoint. This implies that the voice terminal user must invoke Transfer To Data within 15 seconds after far-end answer. Similarly, if an originating voice user calls a voice terminal and both users transfer to data, both ends must transfer within the 15 second time limit.

If the data endpoint is optioned for Command Mode permission, the data endpoint will receive call progress text messages while in the Data Call Setup mode.

g. Data Mode

Data Mode is first entered after successful completion of Data Call Setup. Transparent communication between connected endpoints is provided in Data Mode.

Connecting Configurations

Refer to “Connectivity” in Section 4 for data equipment connections.

Controlling Features

It is possible to originate data calls from a voice terminal with a Transfer to Data button or from data endpoints that support Command Mode (i.e., ASCII data terminals with keyboards and host computers). Several controlling features are provided to allow data endpoints and voice terminals to set up data calls. The following briefly describes the Data Service features used in controlling data calls:

a. Command Mode/Expert Mode

Command Mode and Expert Mode provide an interface to the Data Terminal Dialing feature, the Third-Party Call Setup feature (V2), and permits users to display and change (V2 only) data port options.

b. Data Terminal Dialing

Data Terminal Dialing provides call setup from terminals and host computers.

c. Transfer To Data

Transfer To Data is the preferred method of data call origination from multiline voice terminals equipped with Transfer to Data (DATA) buttons and associated digital data endpoints. The DATA button is associated by DDC with a near end data endpoint. A unique DATA button must be provided for each DDC that the voice terminal is capable of controlling. Associated with each DATA button is an LED that reflects the status of data endpoints as follows:

●Dark–Data endpoint is idle

●Winking–Data endpoint is reserved (preindicated)

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