ITU-X25 Packet layer - Facilities

01 - Reverse charging / Fast select

- Octet : facility code
bits 8-1 01 H
- Octet 1: facility parameter field
bits 8-7 Fast select
bits 6-2 00000
bit 1 Reverse charging
bit 1 Reverse charging
0 Reverse charging not requested

1

Reverse charging requested

bits 8-7 Fast select
0 0 Fast select not requested

0 1

Fast select not requested

1 0

Fast select requested with no restriction on response

1 1

Fast select requested with restriction on response

02 - Throughput class negociation

- Octet : facility code
bits 8-1 02 H
- Octet 1: Coding of throughput class
bits 8-5 From the called DTE
bits 4-1 From the calling DTE
bits dcba Throughput class
0 0 0 0 Reserved

0 0 0 1

Reserved

0 0 1 0

Reserved

0 0 1 1

75

0 1 0 0

150

0 1 0 1

300

0 1 1 0

600

0 1 1 1

1200

1 0 0 0

2400

1 0 0 1

4800

1 0 0 1

4800

1 0 1 0

9600

1 0 1 1

19200

1 1 0 0

48000

1 1 0 1

64000

1 1 1 0

Reserved

1 1 1 1

Reserved

TABLE 30/X.25 (ITU)

03 - Closed user group selection

- Octet : facility code
bits 8-1 03 H
- Octet 1: Closed user group selected for the virtual call
bits 8-5 First digit (binary coded decimal)
bits 4-1 Second digit (binary coded decimal)

08 - Called line address modified notification

- Octet : facility code
bits 8-1 08 H
- Octet 1: facility parameter field
bits 8-1 Called line address modified notification
bits 8 7 6 5 4 3 2 1 Called line address modified notification
0 0 0 0 0 0 0 1 Call redirection due to originally called DTE busy
0 0 0 0 0 1 1 1 Call distribution within a hunt group
0 0 0 0 1 0 0 1 Call redirection due to originally called DTE out of order
0 0 0 0 1 1 1 1 Call redirection due to prior request from originally called DTE for systematic call redirection
1 1 x x x x x x Called DTE originated (a)
1 1 x x x x x x Call deflection by the originally DTE address (b)
TABLE 32/X.25 (ITU)

(a): Each X may be independently set to 0 or 1 by the called DTE and is passed transparently to the calling DTE. Bit 8, when received from the called DTE, and when it is not set to 1, is forced to 1 by the DCE.

(b): The Xs are those set by the originally called DTE in the call deflection selection facility.

09 - Closed user group with outgoing access selection

- Octet : facility code
bits 8-1 09 H
- Octet 1: Closed user group selected for the virtual call
bits 8-5 First digit (binary coded decimal)
bits 4-1 Second digit (binary coded decimal)

41 - Bilateral closed user group selection

- Octet : facility code
bits 8-1 41 H
- Octet 1: Bilateral closed user group selected
bits 8-5 First digit (binary coded decimal)
bits 4-1 Second digit (binary coded decimal)
- Octet 2: Bilateral closed user group selected
bits 8-5 Third digit (binary coded decimal)
bits 4-1 Fourth digit (binary coded decimal)

42 - Packet size

- Octet : facility code
bits 8-1 42 H
- Octet 1: facility parameter field
bits 8-5 0000
bits 4-1 Packet size from the called DTE
- Octet 2: facility parameter field
bits 8-5 0000
bits 4-1 Packet size from the calling DTE

The values available for each direction are as follows:

bits 4 3 2 1 Packet size
0 1 0 0 16

0 1 0 1

32

0 1 1 0

64

0 1 1 1

128

1 0 0 0

256

1 1 0 1

512

1 1 0 0

1024

1 1 1 0

2048

1 1 1 1

4096

43 - Window size

- Octet : facility code
bits 8-1 43 H
- Octet 1: facility parameter field
bit 8 0
bits 7-1 Window size from the called DTE
- Octet 2: facility parameter field
bits 8 0
bits 7-1 Window size from the calling DTE

The values of window coded on bits 7-1 are binary coded.

44 - RPOA selection

- Octet : facility code
bits 8-1 44 H

The parameter field contains the data network identification code DNIC corresponding to the initial RPOA transit network requested.

- Octet 1: Identification code
bits 8-5 First digit (binary coded decimal)
bits 4-1 Second digit (binary coded decimal)
- Octet 2: Identification code
bits 8-5 Third digit (binary coded decimal)
bits 4-1 Fourth digit (binary coded decimal)

49 - Transit delay selection and indication

- Octet : facility code
bits 8-1 49 H
- Octets 1-2: Transit delay
bits 16-1 Number in milliseconds from bit 16 to bit 1 (binary coded). Value from 0 to 65534.

C3 - Call redirection or deflection notification

- Octet : facility code
bits 8-1 C3 H
- Octet 1: Length in octets of facility paramater field
bits 8-1 = n+2, where n is the number of octets necessary to hold the originally called DTE address.
- Octet 2: facility parameter field
bits 8-1 Reason for the call redirection or call deflection
- Octet 3: facility parameter field
bits 8-1 Number of semi-octets in the originally called DTE address
- Octets 4-4+(n-1): facility parameter field
Originally called DTE address (n octets)
bits 8 7 6 5 4 3 2 1 Coding of the reason
0 0 0 0 0 0 0 1 Orig. called DTE busy":
0 0 0 0 0 1 1 1 Call dist. within a hunt group
0 0 0 0 1 0 0 1 Orig. called DTE out of order
0 0 0 0 1 1 1 1 Systematic call redirection
1 1 x x x x x x Call deflection by the originally DTE address (a)
TABLE 31/X.25 (ITU)

(a): The Xs are those set by the originally called DTE in the call deflection selection facility.

D1 - Call deflection selection

- Octet : facility code
bits 8-1 D1 H
- Octet 1: Length in octets of facility parameter field
bits 8-1 = n+2, where n is the number of octets necessary to hold the called address of the DTE to which the call is to be deflected (the alternative DTE).
- Octet 2: facility parameter field
bits 8-1 Reason for the DTE deflecting the call
- Octet 3: facility parameter field
bits 8-1 Number of semi-octets in the alternative DTE address
- Octets 4-4+(n-1): facility parameter field
Alternative DTE address (n octets)
bits 8 7 6 5 4 3 2 1 Reason for the call deflection
1 1 x x x x x x Call DTE originated

 


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updated:  27-Feb-04