$90

Normal clearing—Indicates normal call clearing procedures.

$A2

No circuit available—Indicates the system was not able to perform the requested B-channel allocation. Selection is performed based on class of service (COS), not already in use, and in service (IS) status. This value is returned when a preferred channel is requested.

$A9

Temporary failure—Internal resources necessary to process the call are not available.

$AA

Network congestion—Indicates that the system is temporarily incapable or allocating the call record memory necessary to process an incoming call attempt. This condition arises when the channel ID IE is not processed by the system and the host has not assigned a B-channel quickly enough to free memory for new incoming calls. This condition can also occur from an unusual influx of new call attempts.

$AC

Requested channel not available—System cannot allocate the requested B-channel because that channel is already in use, is not the correct class of service (COS), or is not in active service. This value is returned when an exclusive channel is requested.

$D1

Invalid call reference—D-channel message received with invalid call reference.

$D2

Channel does not exist—D-channel message received with invalid B-channel specified.

$E0

Mandatory IE missing—A mandatory IE was not received in a D-channel message.

$E4

Invalid element contents—An IE was processed with invalid IE coding.