A Calling party subaddress, Connected subaddress információs elemek

The purpose of the Calling party subaddress information element is to identify a subaddress associated with the origin of a call.

For the definition of subaddress, see Recommendation I.330.

               8  7  6  5  4  3  2  1
        1      0  1  1  0  1  1  0  1 = 0x6D  Calling party subaddress
        1      0  1  0  0  1  1  0  1 = 0x4D  Connected subaddress
        2            length  max 23
        3   1 ext b  b  b  a  0  0  0
        4      subaddress information


Type of subaddress (octet 3)
        Bits
        7  6  5
        0  0  0 - NSAP(CCITT Rec. X.213 [23]/ISO 8348 AD2 [24])
        0  1  0 - User specified
        All other values are reserved.

Odd/even indicator (octet 3)
        Bit
        4
        0 - Even number of address signals
        1 - Odd number of address signals
NOTE 1 - The odd/even indicator is used when the type of subaddress is "user specified" and the coding is BCD.

Subaddress information (octets 4, etc.) The NSAP CCITT Rec. X.213/ISO 8348 AD2 address, shall be formatted as specified by octet 4 which contains the Authority and Format Identifier (AFI). The encoding is made according to the "preferred binary encoding" as defined in CCITT Rec. X.213/IAD2 except when used for Terminal selection at the S interface (see Note 3).

For the definition of this type of subaddress, see Recommendation I.334.

For user specified subaddress, this field is encoded according to the user specification, subject to a maximum length of 20 octets. When interworking with X.25 [5] networks BCD coding should be applied.

NOTE 2 - It is recommended that users apply the NSAP subaddress type since this subaddress type allows the use of decimal, binary and IA5 syntaxes in a standardized manner.

NOTE 3 - It is recommended that users apply the Local IDI format (the AFI field coded 50 in BCD) when the subaddress is used for terminal selection purposes at the S interface.

In this case the IA5 character syntax using only digits 0 to 9 shall b for the DSP. Each character is then encoded in one octet according to CCITT Rec. T.50/ISO 646, with zero parity in the most significant position.