Nortel Networks 553-3001-211 manual Call Set-up abort, Make Port Busy on loss of DTR

Page 420 of 894 NT7D16 Data Access card

Call Set-up abort

The user may abandon the call during the dialogue phase using one of the following methods:

•Terminal off-lineThis method is useful for RS-232-C interface only. The equipment drops Data Terminal Ready (DTR) to indicate an idle connection. For example, if the equipment is turned off, the DAC interprets that signal as an idle connection.

•Long break The user sends a break (transmit line held in the OFF or SPACE state) for more than 1.2 seconds. The break is not transmitted to the far end. At the end of the long break, the DAC port initiates call disconnect. The AILU converts the dropping of DTR into a long break for the RS-422 interface. The long break feature can be disabled through the Modify menu on the DAC port.

•Three short breaks When the user equipment transmits three breaks to the far end, the DAC abandons the call. Note that the breaks must be spaced at least 10 msec apart, and all three must occur within 3 seconds.

Make Port Busy on loss of DTR

This feature is implemented by means of the Make Set Busy (MSB) station feature. When this is activated, any attempt to reach the specified Data DN will result in a busy signal.

This application, which operates only in the RS-232-C mode, requires a non-standard RS-232-C interface. Only two of the possible sixteen RS-232-C modes can be used: Mode 8 (DCE, Host, Normal DTR, Manual dial), and Mode 12 (DCE, Terminal, Normal DTR, Manual dial). This feature is configured in the software, and is downloaded to the DAC.

A DTR timeout period is started whenever the DTR signal lead makes the transition to OFF. If DTR is returned to ON within the set time period

(5 seconds), the DAC port operates as if this feature was not activated. If the DTR remains OFF beyond the 5 seconds, the system receives an MSB feature key message. The DAC sends another MSB message when the DTR returns to ON, and the port is able to receive inbound calls.

553-3001-211 Standard 2.00 September 2004