Welltech Dialogic SS7 Protocols ISUP - Manual (Page 68)

Section 6 Interface to Application
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6.6.19 Overload Indication
Note: This message is only applicable to ITU-T operation.
This primitive is used by the ISUP module to indicate that the remote switch
is in overload. It is sent when an Overload message is received from the
remote switch during outgoing call set-up. On receipt of this indication, the
application should re-route the call (if possible).
The Overload indication will be followed by a Release indication (cause value
= 42). Release of the original outgoing circuit does not complete until timer
T3 expires, so preventing the circuit being reused while the remote switch is
in overload.
Message type
OLM (Overload Message)
Mandatory parameters
None
Optional parameters
None
6.6.20 Pre-Release Information Indication
Note: This message is only applicable to ITU-T operation.
This primitive can be issued in all call states up until release. It is used by
the ISUP module to convey end-to-end information.
Message type
PRI (Pre-Release Information)
Mandatory parameters
None
Optional parameters
• Optional forward call indicators
• Optional backward call indicators
• Message compatibility information
• Parameter compatibility information
• Application transport parameter
This parameter may be repeated (see Appendix E: ISUP Repeat
Parameters on page 197 ).
• End of optional parameter