3.36 SS7, DSS1 network specific facility (national use)
The format of the network specific facility parameter field is shown in Figure 37.


8
7
6
5
4
3
2
1


Length of network identification









1a
1
ext.
Type of network identification


Network identification plan





1b
.
.
0
Spare
Network identification







1m
0








2
.
n
Network specific facility indicator







Figure 37/Q.763 - Network specific facility parameter field
The following codes are used in the subfields of the network specific facility parameter field:
a)	Length of network identification
This field contains the length, in octets, of the network identification found in octets 1a, 1b-1m. If the value is 0000 0000, then octets 1a-1m are omitted.
b)	Type of network identification
The following codes are used in the type of network identification subfield:
0 1 0		national network identification
0 1 1		reserved for international network identification (Note)
others		spare
When the type of network identification is coded 010 "national network identification", the network identification plan, and network identification is coded nationally.

	NOTE - The value 011 is reserved for international use, in case the parameter will be accepted for international use in the future.
c)	Network identification plan
d)	Network identification
e)	Network-specific facility indicator
This field is encoded according to the rules specified by the identified network. The network may specify the same coding rule as stimulus type of information elements in Recommendation Q.932. In this case multiple information elements may be included in
this field.


4.5.21 DSS1 Network-specific facilities
The purpose of the Network-specific facilities information element is to indicate which network facilities are to be invoked. The Network-specific facilities information element is coded as shown in Figure 4-27 and Table 4-18. No more than four Network-sp
ecific facilities information elements may be included in a single message.
The maximum length of this information element is network dependent.


Bits
8
7
6
5
4
3
2
1
Octets
Network-specific facilities
0
0
1
0
0
0
0
0
1
Information element identifier
Length of network-specific facilities contents
2
Length of network identification
3
1 ext.
Type of network
identification
Network identification plan
3.1*
0 spare
Network identification (IA5 characters)
3.2*
Network-specific facility specification
4
NOTES
1	Octets 3.1 and 3.2 are only present when the length in octet 3 is non-zero.
2	Octet 3.2 may be repeated as appropriate.
FIGURE  4-27/Q.931
Network-specific facilities information element



TABLE  4-18/Q.931
Network-specific facilities information element

Length of network identification (octet 3)
	This field contains the length, in octets, of the network identification found in octet 3.1 and the repetition of octet 3.2. If the value is "0000 0000", then the default provider (see E.1) is assumed and octets 3.1 and 3.2 are omitted.
Type of network identification (octet 3.1)
	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 3.1)
	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 (octets 3.2, etc.)
	These IA5 characters are organized according to the network identification plan specified in octet 3.1.
Network-specific facilities (octets 4, etc.)
	This field is encoded according to the rules specified by the identified network.