AT&T AT&T manual End-to-End Signaling, Call Disposition, Answering Endpoint, 113

End-to-End Signaling:

Data connections to off-premises destinations require that a conversion resource (pooled modem) be inserted into the connection. Occasionally it is necessary to send additional tones to the remote endpoint after the connection is established to signal the remote equipment. A “mark” character must be included on the DIAL: line to indicate to call processing that the

remaining digits	are to be sent to	the	far end prior	to insertion of the conversion resource
into the connection. The “mark” character marks the				boundary between the digits dialed to
reach a distant	endpoint, and the	digits	used by that	distant endpoint after it has answered.

Pause characters may and usually should follow a “mark” character. An example using a “mark” character and several pause characters is shown below. Dashes are included for readability.

Examples of dialing are as follows:

●DIAL: 3478

●DIAL: 9-1-(201 )-946 -8123,, $,5678

●DIAL: 9%946-8123%%$%5678%137%110

Call Disposition:

Call progress messages corresponding to call progress tones provided to voice terminals are listed in Table 2-H.The message supplied (indicating reorder, busy, ringback) depends on the disposition of the call.

1.When ringback is received the displayed message is “RINGING” (internal calls only). For outside calls, the corresponding call progress message is

“DIALING . . . .“.

2.If the endpoint answers, the displayed message is “ANSWERED” (internal calls only). Then, if the handshake succeeds, a data connection is established. For outside calls, when the system has finished dialing, the message “COMPLETED” is displayed.

3.If the handshake fails because a connection cannot be established between

endpoints (e.g., a port optioned at 9600 baud attempts to talk to a conversion resource t h a t c a n o n l y talk at 300 or 1200 baud), the user receives “INCOMPATIBLE FAR END,” “DISCONNECTED,’” and the data endpoint goes on-hook.

If the far end does not answer, the caller must press Break to terminate the call attempt.

If the disposition of the call is such that TRY AGAIN or BUSY (indicating reorder or intercept and busy respectively) is received, the switch sends “DISCONNECTED” to the data terminal that goes on-hook.

Answering Endpoint:

When the dialed end point is alerted, the user receives “INCOMING CALL-”. (The called terminal will auto-answer if it is turned on. ) If the handshake succeeds, a data connection is established and the “CONNECTED” message is displayed if so optioned. If the handshake fails, the user receives “INCOMPATIBLE FAR END, DISCONNECTED” and the data endpoint goes on-hook.

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