The purpose of the Transit network selection information element is to identify one requested transit network. The Transit network selection information element may be repeated in a message to select a sequence of transit networks through which a call must pass (see Annex C).
The Transit network selection information element is coded as shown in Figure 4-35 and Table 4-25. The maximum length of this information element is network dependent.
Bits |
||||||||
8 |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
Octets |
Transit network selection Information element identifier |
||||||||
0 |
1 |
1 |
1 |
1 |
0 |
0 |
0 |
1 |
Length of transit network selection contents |
2 |
|||||||
1 ext. |
Type of network |
Network identification plan |
3 |
|||||
0 |
Network identification (IA5 characters) |
4 |
||||||
Transit network selection information element
Transit network selection information element
Type of network identification (octet 3) |
|
Bits |
|
7 6 5 |
|
0 0 0 |
User specified |
0 1 0 |
National network identification (Note 1) |
0 1 1 |
International network identification |
All other values are reserved. |
|
Note 1 - In the case that "type of network identification" is coded as 010, "national network identification", "national identification plan" is coded according to national specification. |
|
Network identification plan (octet 3) |
|
Bits |
|
4 3 2 1 |
|
0 0 0 0 |
Unknown |
0 0 0 1 |
Carrier Identification Code (Note 2) |
0 0 1 1 |
Data network identification code (Recommendation X.121) [21] |
All other values are reserved. |
|
Note 2 - Carrier Identification Codes may be an appropriate method of identifying the network serving the remote user. |
|
Network identification (octet 4) |
|
These IA5 characters are organized according to the network identification plan specified in octet 3. |
|