Tech Stuff - Q.931 Message Types
Message Types may take two formats; a one-octet ITU standard or a two-octet Network Specific (which is sometimes a euphemism for proprietary).
Two-Octet Format
This message type is preceeded by an escape octet = 0.
| 8 |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
| 0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
| Message Type |
Message Types
All the message types shown are as 'C' type hexadecimal values rather than the more normal bit format of ITU documentation - for our ease of use. You are welcome to convert them back to binary if that is easier to work with!!
Standard ITU one-octet messages
| Value |
Name |
Direction |
| 0x01 |
ALERTing |
Both |
| 0x02 |
CALL PROCeeding |
Both |
| 0x03 |
PROGress |
Network->User |
| 0x05 |
SETUP |
Both |
| 0x07 |
CONNect |
Both |
| 0x0D |
SETUP ACKnowledge |
Network->User |
| 0x0F |
CONNect ACKnowledge |
Both |
| 0x24 |
HOLD |
Both |
| 0x28 |
HOLD ACKnowledge |
Both |
| 0x30 |
HOLD REJect |
Both |
| 0x31 |
RETrieve |
Both |
| 0x33 |
RETrieve ACKnowledge |
Both |
| 0x37 |
RETrieve REJect |
Both |
| 0x45 |
DISConnect |
Both |
| 0x4D |
RELease |
Both |
| 0x5A |
RELease COMplete |
Both |
| 0x60 |
SEGment |
Network->User |
| 0x62 |
FACility |
Both |
| 0x64 |
REGister |
User->Network |
| 0x75 |
STATUS ENQuiry |
Network->User |
| 0x7B |
INFOrmation |
Both |
| 0x7D |
STATUS |
User->Network |
| 0x7E |
NOTIFY |
Network->User |
Network Specific two-octet messages
Since these message types are typically proprietary or National they are listed under the vendor (or country) value. For the sake of brevity the preceding zero (see above) has been omitted.
National ISDN-1, 2, 3 (North America)
| Value |
Name |
Direction |
| 0xFB |
KEY HOLD |
Network->User |
| 0xFC |
KEY RELease |
Network->User |
| 0xFF |
KEY SETUP |
Network->User |
| 0xFE |
KEY SETUP ACKnowledge |
User->Network |
CUSTOM LUCENT
| Value |
Name |
Direction |
| 0x90 |
CONFerence |
User->Network |
| 0x91 |
CONFerence ACKnowledge |
Network->User |
| 0x92 |
CONFerence REJect |
Network->User |
| 0x93 |
TRANSfer |
User->Network |
| 0x94 |
TRANSfer ACKnowledge |
Network->User |
| 0x95 |
TRANSfer REJect |
Network->User |
| 0x96 |
ASSOCiated |
Network->User |
| 0x97 |
ASSOCiated ACKnowledge |
User->Netwok |
| 0x98 |
DROP |
User->Network |
| 0x99 |
DROP ACKnowledge |
Network->User |
| 0x9A |
DROP REJect |
Network->User |
| 0x9B |
HOLD |
User->Network |
| 0x9C |
HOLD ACKnowledge |
Network->User |
| 0x9D |
HOLD REJect |
Network->User |
| 0x9E |
RECONNect |
User->Network |
| 0x9CF |
RECONNect ACKnowledge |
Network->User |
| 0xB0 |
RECONNect REJect |
Network->User |
| 0xB1 |
REDIRect |
Network->User |
| 0xF7 |
MANagement INFOrmation |
Both |
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