X25AM Programming Manual

Introduction
X25AM Programming Manual—527201-001
1-6
Call Setup and Call Clearing Packets
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The application is waiting for a call with an OPEN and a CONTROL 11.
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If a port number is used, the called port number equals the subdevice port number.
The called port number is derived from the digits that remain after counting the
digits specified in the incoming address.
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If the indicated packet size is not the configured packet size, the subdevice is
configured to negotiate packet size.
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If reverse charges are indicated, the subdevice is configured to accept reverse
charges.
If the incoming call has no port number or the port number is greater than 9999, then
the call is assigned to a subdevice that has no port number.
If the subdevice to which the call is first assigned does not accept the call, then X25AM
resumes searching with the next subdevice. If X25AM cannot find a subdevice to
accept the call, it clears the call (with a cause of 0 and a diagnostic of 129).
HP recommends that you use port numbers when incoming calls must be assigned to
specific subdevices.
Call Setup and Call Clearing Packets
This section discusses:
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The four types of Call Setup packets
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The four types of Call Clearing packets
It also contains a brief description of the Restart, Clear, Reset, and Diagnostic Packets.
The subsection following the packet descriptions contains details about the various
subscription parameters.
Some aspects of packet processing are treated differently by individual installations.
Some of these differences affect how incoming and outgoing information is handled.
X25AM support of Call Setup and Call Clearing packets is described in the following
paragraphs.
Types of Packets
In the call setup phase there are four types of Call Setup packets. These packet types
appear only on an SVC during the call set-up phase.
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Incoming Call
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Call Accepted
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Call Request
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Call Connected