Instruction manual

Data Services Overview
e.
Data Terminal Dialing Mode
Data Terminal Dialing is a data feature accessed via Command Mode. It provides a
procedure to establish data calls without the use of a voice terminal. Data Terminal
Dialing supports both on-premises and off-premises data calls (with the support of
the System 25 Modem Pooling feature).
Dialed digits are entered from the data
terminal keyboard or host computer (using a program compatible with Data Terminal
Dialing protocol). Call progress text messages are sent to the terminal in place of
call progress tones.
Upon completion of digit entry, Data Call 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 either 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, and permits users to display and change
data port options.
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