Why should we use GT-xin Fang's internal organization of information?

1.1 why use GT:

In the signaling network, each signaling point has a code that uniquely represents the existence of this signaling point. This code is called a signaling address. In China, the length of the signaling address is defined as 24 bits, however, it is sometimes inconvenient to identify a signaling point with such a 24-bit address. For example, a switch often needs to determine the route of the signaling message based on the first few digits of the called number, this requires the called number as part of the signaling address. The solution to this problem in the signaling system is to introduce the GT address, which is obviously different from the 24 signaling address, it requires a set of special definitions. All signaling points comply with this definition and interact with signaling messages.

We know that the signaling address includes the MTP layer address and SCCP layer address. When sending a message, the switch translates the Message address into the MTP layer signaling address based on the master and called addresses of the SCCP layer, the GT address mentioned above exists in the SCCP layer.

1.2 SCCP address Overview:

SCCP has two addresses: The caller and the called address. They have the same format definition.

L address

8	7	6	5	4	3	2	1
Address indicator (1 byte)
Signalling point code (3 byte)
Subsystem number (1 byte)
Global title (N byte)

L address indicator

8	7	6	5	4	3	2	1
Reserved for national use	Routing indicator	Global title indicator				SSN indicator	Point Code Indicator

Pointcodeindicator: A "1" in BIT 1 indicates that the address contains a signalling point code.

SSN indicator: A "1" in BIT 2 indicates that the address contains a subsystem number.

Global title indicator:

Bit 6543

0000 no global title shortded

0001 global title shortdes nature of address indicator only

0010 global title shortdes translation type only3)

0011 global title shortdes translation type, numbering plan and encoding Scheme3)

0100 global title shortdes translation type, numbering plan, encoding scheme and nature of address indicator

Routing indicator:

A "0" in BIT 7 indicates that routing shoshould be based on the global title in the address.

A "1" in BIT 7 indicates that routing shoshould be based on the destination point code in the MTP routing label and the subsystem number information in the called party address.

L global title:

There are four types of GT addresses, which are described as follows. The address information section is the specific address information, which is in BCD format and has an indefinite length. The rest are additional bytes, for a network or a vswitch, this Part has the same code value. For a vswitch, the address information part has two types: fixed type and variable type, A fixed type indicates that each vswitch corresponds to a fixed code value to uniquely describe the vswitch. A variable type indicates that the vswitch has multiple codes corresponding to it. In this case, the first few digits of address information correspond to the same vswitch, the following address information is changeable.

Global title Indicator = 0001

8	7	6	5	4	3	2	1
O/E	Nature of address indicator							Octet 1
Address information								Octet 2 and further

Global title Indicator = 0010

8	7	6	5	4	3	2	1
Translation type								Octet 1
Address information								Octet 2 And further

Global title Indicator = 0011

8	7	6	5	4	3	2	1
Translation type								Octet 1
Numbering Plan				Encoding scheme				Octet 2
Address information								Octet 3 And further

Global title Indicator = 0100

8	7	6		5		4	3	2	1
Translation type										Octet 1
Numbering Plan					Encoding scheme					Octet 2
Spare			Nature of address indicator							Octet 3
Address information										Octet 4 And further