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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 Dialogic, use the SS7 ISUP Message Query message.

Finding Parameter IDs

Depending on the telecommunications standard being used, you find the IDs for optional parameters listed in the specifications issued by ITU or ANSI.

Example

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 | Frame | 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

See Integrated Services Digital Network User Part.
See Signaling System Number Seven.
American National Standards Institute. ANSI administers and coordinates the U.S. voluntary standardization and conformity assessment system for the
telecommunications industry. More details on these standards may be
viewed at www.ansi.org.
International Telecommunications Union (UN)
A number that addresses a node in a SS7 network.
International Telephone Union – Telecommunications sector (UN)
ITU-TSS Publication on Formats and Codes (ISUP)
A group of data bits in a specific format, with a flag at each end to indicate the beginning and the end of the frame.
Most Significant Bit
Least Significant Bit