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Modifying the Format of an ISUP Message
Overview
You modify the format of an ISUP message using the SS7 ISUP Message Format Configure message. ISUP messages can be modified by removing or adding optional parameters that are supported in the applicable ANSI or ITU specification. You must include all of the mandatory parameters that are included in the format of an ISUP message.
To find the format of an ISUP message supported by Excel, use the SS7 ISUP Message Query message.
Depending on the telecommunications standard being used, you find the IDs for optional parameters listed in the specifications issued by ITU or ANSI.
The example script file below shows the SS7 ISUP Message Format Configure message being used to change the format of the RELEASE message. The Release message format includes 13 optional parameters:
• User-to-User Information
• Automatic Congestion Level
• Parameter Capability Information
• Access Delivery Information
• Redirection Number
• Remote Operations
• Network Specific Facilities
• Redirection Information
• Access Transport
• Signaling Point Code
• User-to-User Indicators
• Display Information
• Redirection Number Restriction
Example Configuration Script File
This script file, sent by the host, configures the Release message format to include only four optional parameters. This example uses the optional parameter IDs in the ITU-T Q.763 specification.
00 20 00 6B 00 00 FF 00 01 08 01 00 04 0C 01 00 01 12 02 00 01 04 03 01 00 27 01 01 0C 03 0A 20 01 81
Example Message Format Table with Values
The table below interprets the information provided in the script file shown earlier in this section. The Release message has only one mandatory fixed parameter: Message ID. Because the ISUP Message Index and ISUP Message ID fields indicate this parameter ID, the parameter ID does not need to be repeated in the MFP 1: ID field.
Note:
Maximum Length of 0x00 means infinity.
Byte |
Field Description |
Value |
---|---|---|
0 |
0xFE |
|
1 |
Length, MSB |
0x00 |
2 |
Length, LSB |
0x2C |
3 |
Message Type, MSB |
0x00 |
4 |
Message Type, LSB |
0x6B |
5 |
Reserved |
0x00 |
6 |
Sequence Number |
0x00 |
7 |
Logical Node ID |
0xFF |
8 |
Address Method |
0x00 |
9 |
Number of Address Elements |
0x01 |
10 |
Address Type |
0x08 (SS7 Stack) |
11 |
Data Length |
0x01 |
12 |
Data[0] SS7 Stack ID |
0x00 |
13 |
ISUP Message Index |
0x04 |
14 |
ISUP Message ID |
0x0C |
15 |
ISUP Message Priority |
0x01 |
16 |
Number of Mandatory Fixed Parameters (MFP) |
0x00 |
17 |
Number of Mandatory Variable Parameters (MVP) |
0x01 |
18 |
MVP 1: ID |
0x12 (Cause Indicators) |
19 |
MVP 1: Minimum Length |
0x02 |
20 |
MVP 1: Maximum Length |
0x00 |
21 |
Optional Parameters Allowed |
0x01 (Yes) |
22 |
Number of Optional Parameters |
0x04 |
23 |
OP 1: ID |
0x03 (Access Transport) |
24 |
OP 1: Minimum Length |
0x01 |
25 |
OP 1: Maximum Length |
0x00 |
26 |
OP 2: ID |
0x27 (Auto. Congestion Level) |
27 |
OP 2: Minimum Length |
0x01 |
28 |
OP 2: Maximum Length |
0x01 |
29 |
OP 3: ID |
0x0C (Redirection Number) |
30 |
OP 3: Minimum Length |
0x03 |
31 |
OP 3: Maximum Length |
0x0A |
32 |
OP 4: ID |
0x20 (User to User Information) |
33 |
OP 4: Minimum Length |
0x01 |
34 |
OP 4: Maximum Length |
0x81 |
35 |
Checksum |
0x2A |