SS7 Enhancements

Release 8.3.1 includes the following SS7 features.

• ISDN Query D-Channel Enhancement

• PPL Event Indication for Timer Expiration

ISDN Query D-Channel Enhancement

Overview

Currently, the ISDN software does not provide a way of knowing where the D-Channel information (span channel) is residing and the number of D-channels supported by an ISDN Series 3 card.

This information is available through the debug port, but a querying capability was not supported by the Card Status Query, Card Status Report and ISDN Query messages.

This feature will support only the querying capability of the ISDN Query message.

New Functionality

The ISDN Query message (0x0063) has been changed as follows:

• The message will support Slot AIB in order to validate the ISDN Series 3 card data.

• The message will support a new Query Type, 0x0E Configured D Channels.

• The Query Subtype, 0x0E Configured D Channels is:

0x00 None

• The query response will contain the maximum number of D-channels that can be configured (span channel), where the D-channels are configured, and the information regarding whether it is a primary or secondary D-channel.

• The Query Type, 0x0E Configured D Channels message responses are as follows:

0x0E Configured D Channels

Message Responses:

Data [0, 1] Maximum Number of D-Channels Configurable (MSB, LSB)

Data [2, 3] D-Channel 1 - Logical Span ID (MSB, LSB)

Data [4] D-Channel 1 - Channel

Data [5] Primary Flag (0x00 if Primary, 0x01 if Secondary)

:

:

Data [n -]

NOTE: D-channels that are not configured will return a value of 0xFF FF FF FF.

The response will contain ACK or NACK according to the validation result. If the message is successfully processed, the maximum number of D-Channels that can be configured for the card (span channel) and the primary/secondary status of the D-Channel will be sent back to the host.

Refer to the ISDN Query 0x0063 message in the API Reference.

PPL Event Indication for Timer T7 Expiration

Currently, the Outseize Control message generates an Initial Address Message (IAM) to the network. If the Awaiting Address Complete timer T7 expires in 20 to 30 seconds, a Release (REL) message is automatically sent to the CSP. An Outseize Control ACK is then sent to the host with response status 0x1B (Outseize Failure No Acknowledge). Upon receipt of a Release Complete (RLC) message, a Channel Released with Data message is sent to the host. Since the Channel Released with Data message does not provide a cause code, the host assumes that if no cause code was received that the call failed due to T7. There is not enough information for the host to determine why the call failed.

Incorrect cause codes are then generated to inbound calls, since the network cannot provide a cause code. For example, this condition can cause discrepancies in Call Detail Records (CDRs) for customers when an inbound call is rejected with Normal Call Clearing and an outbound call is rejected with No User Responding.

New T7 Functionality

To rectify this condition, PPL Component ISUP CPC (0x12), for both ITU and ANSI, has been changed as follows:

• The existing PPL Config Byte 0x11 will be used to enable or disable the T7 timer expiration.

• A new PPL Event Indication ID 0x9A (T7 expiration) has been added.

The T7 timer expire is enabled by setting PPL Config Byte 0x11 to 0x01. Upon sending the Initial Address Message (IAM), the Awaiting Address Complete timer (T7) is started. If timer T7 expires (after 20 to 30 seconds) a new PPL Event Indication with ID 0x9A is sent to the host and the connection is released.

Refer to the ISUP CPC (0x0012) PPL Component in Chapter 7, SS7 PPL Information in the CSP Developer’s Guide: Common Channel Signaling.