The purpose of the message type is to identify the function of the message being sent.
The message type is the third part of every message. The message type is coded as shown in Figure 4-6 and Table 4-2.
Bit 8 is reserved for possible future use as an extension bit.
Bits |
||||||||
8 |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
Octet |
0 |
Message type |
1 |
||||||
Message type
Message types
Bits |
|
8 7 6 5 4 3 2 1 |
|
0 0 0 0 0 0 0 0 |
Escape to nationally specific message type (Note) |
0 0 0 – – – – – |
Call establishment message: |
0 0 0 0 1 |
- ALERTING |
0 0 0 1 0 |
- CALL PROCEEDING |
0 0 1 1 1 |
- CONNECT |
0 1 1 1 1 |
- CONNECT KNOWLEDGE |
0 0 0 1 1 |
- PROGRESS |
0 0 1 0 1 |
- SETUP |
0 1 1 0 1 |
- SETUP ACKNOWLEDGE |
0 0 1 – – – – – |
Call information phase message: |
0 0 1 1 0 |
- RESUME |
0 1 1 1 0 |
- RESUME ACKNOWLEDGE |
0 0 0 1 0 |
- RESUME REJECT |
0 0 1 0 1 |
- SUSPEND |
0 1 1 0 1 |
- SUSPEND ACKNOWLEDGE |
0 0 0 0 1 |
- SUSPEND REJECT |
0 0 0 0 0 |
- USER INFORMATION |
0 1 0 – – – – – |
Call clearing messages: |
0 0 1 0 1 |
- DISCONNECT |
0 1 1 0 1 |
- RELEASE |
1 1 0 1 0 |
- RELEASE COMPLETE |
0 0 1 1 0 |
- RESTART |
0 1 1 1 0 |
- RESTART ACKNOWLEDGE |
0 1 1 – – – – – |
Miscellaneous messages: |
0 0 0 0 0 |
- SEGMENT |
1 1 0 0 1 |
- CONGESTION CONTROL |
1 1 0 1 1 |
- INFORMATION |
0 1 1 1 0 |
- NOTIFY |
1 1 1 0 1 |
- STATUS |
1 0 1 0 1 |
- STATUS ENQUIRY |
Note - When used, the message type is defined in the following octet(s), according to the national specification. |
|