Tech Stuff - Q.931 Progress Information Element
The Progress Information Element provides one or more octets that describe events that occur during the life of the call. Q.931 Section 4.5.23.
Progress Format
The Progress IE is variable length with the following format:
| 8 |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
Octet |
| 0 |
Progress IE (0x1E) |
1 |
| length of the Progress Information |
2 |
| 1 |
coding std. |
0 |
Location |
3 |
| 1 |
Progress description |
4 |
NOTE: Bit 8 of octets 3 and 4 above is the Extension bit and is coded as follows:
- Extension bit = 0 more information for this field follows.
- Extension bit = 1 last octet of this field.
Coding Standard
| 7 |
6 |
Meaning |
| 0 |
0 |
ITU standardized coding |
| 1 |
1 |
Standard specific to Location field |
Location
| 4 |
3 |
2 |
1 |
Meaning |
| 0 |
0 |
0 |
0 |
User |
| 0 |
0 |
0 |
1 |
Private network serving location user |
| 0 |
0 |
1 |
0 |
Public network serving local user |
| 0 |
0 |
1 |
1 |
Transit network |
| 0 |
1 |
0 |
0 |
Public network serving remote user |
| 0 |
1 |
0 |
1 |
Remote private network |
| 0 |
1 |
1 |
1 |
International network |
| 1 |
0 |
1 |
0 |
Network beyond interworking point |
Progress Indicator
The following table shows the hexadecimal value with the extension bit set, without the extension bit set and the decimal value (without the extension bit set).
Hex
w Ext |
Hex
wo Ext |
Dec |
Meaning |
| 0x81 |
0x01 |
1 |
Call is not end-to-end ISDN or may be in-band information |
| 0x82 |
0x02 |
2 |
Destination call address is non-ISDN |
| 0x83 |
0x03 |
3 |
Origination call address is non-ISDN |
| 0x84 |
0x04 |
4 |
Call has returned to the ISDN |
| 0x88 |
0x08 |
8 |
Inband treatment has been applied |
| 0x8A |
0x0A |
10 |
Delay in response at the call interface |
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