Telecommunications - X.25 Facilities

Level 3 facilities

Reverse Charge

Extended Formats

Packet size negotiation

Window size negotiation

Fast select

Closed user group

Call redirection

Multiline

Call Statistics

International facilities

1984 facilities

Public Network Facilities


Facility Length Field

This indicates the length of facility field in bytes.


Level 3 facilities


per-call facility fields

0 1 0 0 0 0 1 0 42 packet size
0 1 0 0 0 0 1 1 43 window size
0 0 0 0 0 0 1 0 02 throughput class negotiation
0 0 0 0 0 0 1 1 03 closed user group - basic format
0 1 0 0 0 1 1 1 47 closed user group - extended format
0 0 0 0 1 0 0 1 09 closed user group - with O/G access
0 1 0 0 1 0 0 0 48 closed user group - extended +O/G
0 1 0 0 0 0 0 1 41 closed user group - bilateral
0 0 0 0 0 0 0 1 01 reverse charging/fast select
1 1 0 0 0 1 1 0 C6 Network user Identification
0 0 0 0 0 1 0 0 04 Charging Information - requesting service
1 1 0 0 0 1 0 1 C5 Charging Information - monetary unit
1 1 0 0 0 0 1 0 C2 Charging Information - segment count
1 1 0 0 0 0 0 1 C1 Charging Information - call duration
0 1 0 0 0 1 0 0 44 RPOA selection - basic format
1 1 0 0 0 1 0 0 C4 RPOA selection - extended format
0 0 0 0 1 0 0 0 08 Called line address modified
1 1 0 0 0 0 1 1 C3 Call Redirection Notification
0 1 0 0 1 0 0 1 49 Transit delay selection and indication
v v
0 0 single byte parameter field
0 1 double byte parameter field
1 0 triple byte parameter field
1 1 variable length parameter field
DTE facilities (1984)
1 1 0 0 1 0 1 1 CB Calling address extension
1 1 0 0 1 0 0 1 C9 Called address extension
0 0 0 0 1 0 1 0 0A Minimum Throughput Class Negotiation
1 1 0 0 1 0 1 0 CA end-to-end transit delay
0 0 0 0 1 0 1 1 0B Expedited data negotiation



Some facilities (eg reverse charging) are required on a per call basis:

byte 1 2 3 type Call Request Incoming Call Call Accepted (fast select) Call Connected (fast select)
00 00 - National options marker (calling network) Y Y Y Y
00 FF - " " " (called network) Y Y Y Y
01 00 - no reverse charging Y EF N N
01 01 - reverse charging Y option N N
01 C0 - fast select (restricted response) EF EF N N
01 80 - fast select (unrestricted response) EF EF N N
01 C1 - reverse charging and fast select (restricted response) EF EF N N
01 81 - reverse charging and fast select (unrestricted response) EF EF N N
02 xx Throughput (not Public Network)
03 xx - Closed user group option option option option
43 0x 0x Window size EF EF EF EF
42 0x 0x Packet size EF EF EF EF
44 ROPA selection (not Public Network)
C1 04 xxxx call duration N N option option
C2 08 xxxxxxxx segment count N N option option

Public Network Facilities

byte subscription type
1 2 3 or per call
00 00 - - National options marker (calling network)
00 FF - - " " " (called network)
01 00 - no reverse charging or call accept
01 01 - og - per call reverse charging
ic - subscription
01 C0 - subscription fast select (restricted response)
01 80 - (includes extended fast select (unrestricted response)
01 C1 - format) reverse charging and fast select (restricted response)
01 81 - reverse charging and fast select (unrestricted response)
02 xx - not Public Network Throughput
03 xx - Closed user group
43 0x 0x requires extended format Window size
42 0x requires extended format Packet size
44 not Public Network RPOA selection
C1 04 xxxx call duration
C2 08 xxxxxxxx segment count



Some facilities (eg reverse charging) are required on a per call basis:

byte

1 2 3

type Call Request Incoming Call Call Accepted fast select Call Connected fast select
00 00 National options marker (calling network) Y Y Y Y
00 FF " " " (called network) Y Y Y Y
01 00 no reverse charging Y EF N N
01 01 reverse charging Y option N N
01 C0 fast select (restricted response) EF EF N N
01 80 fast select (unrestricted response) EF EF N N
01 C1 reverse charging and fast select (restricted response) EF EF N N
01 81 reverse charging and fast select(unrestricted response) EF EF N N
02 xx Throughput (not Public Network)
03 xx Closed user group option option option option
43 0x 0x Window size EF EF EF EF
42 0x 0x Packet size EF EF EF EF
44 ROPA selection (not Public Network)
C1 04 xxxx call duration N N option option
C2 08 xxxxxxxx segment count N N option option

byte subscription type

1 2 3 or per call

-- -- -- ------------ ----

00 00 - - National options marker (calling network)

00 FF - - " " " (called network)

01 00 - no reverse charging or call accept

01 01 - og - per call reverse charging

ic - subscription

01 C0 - subscription fast select (restricted response)

01 80 - (includes extended fast select (unrestricted response)

01 C1 - format) reverse charging and fast select (restricted response)

01 81 - reverse charging and fast select (unrestricted response)

02 xx - not Public Network Throughput

03 xx - Closed user group

43 0x 0x requires extended Window size

format

42 0x requires extended Packet size

format

44 not Public Network RPOA selection

C1 04 xxxx call duration

C2 08 xxxxxxxx segment count


non-ext format to non-ext format

non-ext format non-ext format

DTE DCE DCE DTE

-- CALL REQ -? call cannot contain packet or

p=256 w=7 window size facilities.

if it does it will be cleared

?- CLEAR 0341 - by the network 0341

-- CALL REQ -? -- INC CALL -? incoming call will have calling

and called addresses.

?- CALL CON -- ?- CALL ACC -- call acc cannot contain packet

or window size or addresses

only the default packet & window of 128 and 2 will be used.


11.10 non-ext format to ext format

non-ext format ext format

DTE DCE DCE DTE

-- CALL REQ -? -- INC CALL -? call cannot contain packet or

window size facilities.

if it does it will be cleared

by the network 0341

incoming call will have default

packet and window size plus

calling and called addresses

?- CALL CON -- ?- CALL ACC -- call acc packet/window facility

and addresses optional

if included facilities must be

default.

call con contains no facilities

or addresses.


11.11 ext format to non-ext format

ext format non-ext format

DTE DCE DCE DTE

-- CALL REQ -? -- INC CALL -? if call contains packet or

p=256 w=7 p=128 w=2 window size facilities they

will be negotiated down by the

network.

incoming call will have default

packet and window size plus

calling and called addresses

?- CALL CON -- ?- CALL ACC -- call acc packet/window facility

p=128 w=2 and addresses optional

if included facilities must be

default.

call con contains no facilities

or addresses.


11.12 ext format to ext format

ext format ext format

DTE DCE DCE DTE

-- CALL REQ -? -- INC CALL -? call can contain packet/window

size facilities.

?- CALL CON -- ?- CALL ACC -- call acc packet/window facility

and addresses optional (length field must be included) if included facilities can only be packet and window size and must negotiate toward default.


FACILITIES VIA International Public Network

 


 


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