The purpose of the BC IE is to indicate a requested Recommendation I.231 bearer service to be provided by the network. It contains only information which may be used by the network. The use of the BC IE in relation to compatibility checking is possible. No default BC may be assumed by the absence of this IE. Future extensions to the codings of the BC IE should not be in conflict with the initially defined coding of the Low layer compatibility IE.
8 7 6 5 4 3 2 1
1 0 0 0 0 0 1 0 0 = 4
2 length max 12
3 1 ext b b a a a a a
4 1 ext d d c c c c c
4.1 1 ext e e e e e e e
5 0/1 ext 0 1 f f f f f
5a 0/1 ext i h g g g g g
5b 0/1 ext n n m l k j 0
5b 0/1 ext t s r q p o 0
5c 0/1 ext w w v v u u u
5d 1 ext y x x x x x x
6 1 ext 1 0 p2 p2 p2 p2 p2
7 1 ext 1 1 p3 p3 p3 p3 p3
ext=1 last octet
ext=0 the octet continues through the last octet
a) Information transfer capability (octet 3)
Bits
54321
00000 - Speech
01000 - Unrestricted digital information
01001 - Restricted digital information
10000 - 3.1 kHz audio
10001 - Unrestricted digital information with tones/announcements (Note 2)
11000 - Video
All other values are reserved.NOTE 2 - Unrestricted digital information with tones/announcements (UDI-TA) is the new information transfer attribute value that had previously been named "7 kHz audio" in Recommendation Q.931 (1988).
b) Coding standard (octet 3)
Bits
76
00 - CCITT standardized coding as described below
01 - ISO/IEC standard (Note 1)
10 - National standard (Note 1)
11 - Standard defined for the network (either public or private) present on the network side of the interface (Note 1)
NOTE 1 - These other coding standards should be used only when the desired bearer capability cannot be represented with the CCITT-standardized coding.
c) Information transfer rate (octet 4)
Bits
5 4 3 2 1 Circuit mode Paquet-mode
0 0 0 0 0 - This code shall be used for packet mode calls
1 0 0 0 0 64 kbit/s -
1 0 0 0 1 2 x 64 kbit/s -
1 0 0 1 1 384 kbit/s -
1 0 1 0 1 1536 kbit/s -
1 0 1 1 1 1920 kbit/s -
1 1 0 0 0 Multirate (64 kbit/s base rate)
All other values are reserved.
NOTE 1 - When the information transfer rate 2x64 kbit/s is used, the coding of octets 3 and 4 refer to both 64 kbit/s channels.NOTE 2 - Additional attributes are defined in Table 4-7.
d) Transfer mode (octet 4)
Bits
7 6
0 0 - Circuit mode
0 1 - Packet mode
All other values are reserved.
e) Rate multiplier (octet 4.1)
This octet is required if octet 4 indicates multirate (64 kbit/s base rate). Otherwise, it shall not be present.
f) User information layer 1 protocol (octet 5)
Bits
7 6
0 1 - Layer 1 ident
Bits
5 4 3 2 1
0 0 0 0 1 - CCITT standardized rate adaption V.110 and X.30.
This implies the presence of octet 5a and optionally
octets 5b, 5c and 5d as defined below.
0 0 0 1 0 - Recommendation G.711 m-law
0 0 0 1 1 - Recommendation G.711 A-law
0 0 1 0 0 - Recommendation G.721 32 kbit/s ADPCM and Recommendation I.460.
0 0 1 0 1 - Recommendations H.221 and H.242
0 0 1 1 1 - Non-CCITT standardized rate adaption.
This implies the presence of octet 5a and,
optionally, octets 5b, 5c and 5d.
The use of this code point indicates that the user rate
specified in octet 5a is defined by the user.
Additionally, octets 5 if present, are defined consistent
with the user specified rate adaption.
0 1 0 0 0 - CCITT standardized rate adaption V.120.
This implies the presence of octets 5a and 5b as defined below,
and optionally octets 5c and 5d.
0 1 0 0 1 - CCITT standardized rate adaption X.31. HDLC flag stuffing.
All other values are reserved.
NOTE - If the transfer mode is "circuit mode", and if the information transfer capability is "unrestricted digital information" or "restricted digital information"; and if the user information layer 1 protocol is to be identified only to the addressed ent
ity octet 5 shall be omitted. If the transfer mode is packet mode, octet 5 may be omitted. Otherwise, octet 5 shall be present.Octet 5a
g) User rate (octet 5a)NOTE2 - This octet may be present if octet 3 indicates unrestricted digital information and octet 5 indicates either of the CCITT standardized rate adaptions V.110 and X.30 or V.120 [9]. It may also be present if octet 3 indicates 3.1 kHz audio and octet 5 indicates G.711.
Bits
5 4 3 2 1
0 0 0 0 0 - Rate is indicated by E-bits specified in Rec. I.460 [15] or may be negotiated in-band
0 0 0 0 1 - 0.6 kbit/s Recommendations V.6 and X.1
0 0 0 1 0 - 1.2 kbit/s Recommendation V.6
0 0 0 1 1 - 2.4 kbit/s Recommendations V.6 and X.1
0 0 1 0 0 - 3.6 kbit/s Recommendation V.6
0 0 1 0 1 - 4.8 kbit/s Recommendations V.6 and X.1
0 0 1 1 0 - 7.2 kbit/s Recommendation V.6
0 0 1 1 1 - 8 kbit/s Recommendation I.460
0 1 0 0 0 - 9.6 kbit/s Recommendations V.6 and X.1
0 1 0 0 1 - 14.4 kbit/s Recommendation V.6
0 1 0 1 0 - 16 kbit/s Recommendation I.460
0 1 0 1 1 - 19.2 kbit/s Recommendation V.6
0 1 1 0 0 - 32 kbit/s Recommendation I.460
0 1 1 1 0 - 48 kbit/s Recommendations V.6 and X.1
0 1 1 1 1 - 56 kbit/s Recommendation V.6
1 0 1 0 1 - 0.1345 kbit/s Recommendation X.1
1 0 1 1 0 - 0.100 kbit/s Recommendation X.1
1 0 1 1 1 - 0.075/1.2 kbit/s Rec. V.6 and X.1 (Note 3)
1 1 0 0 0 - 1.2/0.075 kbit/s Rec. V.6 and X.1 (Note 3)
1 1 0 0 1 - 0.050 kbit/s Recommendations V.6 and X.1
1 1 0 1 0 - 0.075 kbit/s Recommendations V.6 and X.1
1 1 0 1 1 - 0.110 kbit/s Recommendations V.6 and X.1
1 1 1 0 0 - 0.150 kbit/s Recommendations V.6 and X.1
1 1 1 0 1 - 0.200 kbit/s Recommendations V.6 and X.1
1 1 1 1 0 - 0.300 kbit/s Recommendations V.6 and X.1
1 1 1 1 1 - 12 kbit/s Recommendation V.6
All other values are reserved.
NOTE 3 - The first rate is the transmit rate in the forward direction of the call. The second rate is the transmit rate in the backward direction of the call.
h) Negotiation (octet 5a)
Bits
6
0 In-band negotiation not possible
1 In-band negotiation not possible
NOTE 2 - See Rec. V.110 and X.30 or modem type recommendation
i) Synchronous/Asynchronous (octet 5a)
Bit
7
0 Synchronous data
1 Asynchronous data
NOTE 1 - Octets 5b - 5d may be omitted in the case of synchronous user rates.
NOTE 3 - This octet is significant only if octet 5 indicates CCITT standardized rate adaption (see Recommendation V.110 and X.30Octet 5b for V.110 and X.30 rate adaption
j) Flow control on reception (Rx) (octet 5b) (Note 7)
Bit
2
0 Cannot accept data with flow control mechanism (i.e. sender does not support this optional procedure)
1 Can accept data with flow control mechanism (i.e. sender does support this optional procedure)
NOTE 7 - Refers to transmission in the backward direction of the call
NOTE 8 - See Recommendations V.110 and X.30.
k) Flow control on transmission (Tx) (octet 5b) (Note 5)
Bit
3
0 Not required to send data with flow control mechanism
1 Required to send data with flow control mechanism
NOTE 5 - Refers to transmission in the forward direction of the call.
NOTE 6 - See Recommendations V.110 and X.30.
l) Network independent clock (NIC) on reception (Rx) (octet 5b) (Note 3)
Bit
4
0 Cannot accept data with network independent clock (i.e. sender does not support this optional procedure)
1 Can accept data with network independent clock (i.e. sender does support this optional procedure)
NOTE 3 - Refers to transmission in the backward direction of the call.
NOTE 4 - See Recommendations V.110 [7] and X.30 [8].
m) Network independent clock (NIC) on transmission (Tx) (octet 5b) (Note 1)
Bit
5
0 Not required to send data with network independent clock
1 Required to send data with network independent clock
NOTE 1 - Refers to transmission in the forward direction of the call.
NOTE 2 - See Rec. V.110 and X.30.
n) Intermediate rate (octet 5b)
Bits
7 6
0 0 Not used
0 1 8 kbit/s
1 0 16 kbit/s
1 1 32 kbit/s
Octet 5b for V.120 rate adaption
o) In-band/out-band negotiation (octet 5b)
Bit
2
0 Negotiation is done with USER INFORMATION messages on a temporary signalling connection
1 Negotiation is done in-band using logical link zero
p) Assignor/assignee (octet 5b)
Bit
3
0 Message originator is "Default assignee"
1 Message originator is "Assignor only"
q) Logical link identifier negotiation (octet 5b)
Bit
4
0 Default, LLI = 256 only
1 Full protocol negotiation (Note)
NOTE - A connection over which protocol negotiation will be executed is
indicated in bit 2 of octet 5b.
r) Mode of operation (octet 5b)
Bit
5
0 Bit transparent mode of operation
1 Protocol sensitive mode of operation
s) Multiple frame establishment support in data link (octet 5b)
Bit
6
0 Multiple frame establishment not supported. Only UI frames allowed
1 Multiple frame establishment supported
t) Rate adaption header/no header (octet 5b)
Bit
7
0 Rate adaption header not included
1 Rate adaption header included
u) Parity information (Octet 5c)
Bits
3 2 1
0 0 0 Odd
0 1 0 Even
0 1 1 None
1 0 0 Forced to 0
1 0 1 Forced to 1
All other values are reserved.
v) Number of data bits excluding parity Bit if present (octet 5c)
Bits
5 4
0 0 Not used
0 1 5 bits
1 0 7 bits
1 1 8 bits
w) Number of stop bits (octet 5c)
Bits
7 6
0 0 Not used
0 1 1 bit
1 0 1.5 bits
1 1 2 bits
x) Modem type (octet 5d)
Bits
6 5 4 3 2 1
0 0 0 0 0 0
through national use
0 0 0 1 0 1
0 1 0 0 0 1 Recommendation V.21 [55]
0 1 0 0 1 0 Recommendation V.22 [56]
0 1 0 0 1 1 Recommendation V.22 bis [57]
0 1 0 1 0 0 Recommendation V.23 [58]
0 1 0 1 0 1 Recommendation V.26 [59]
0 1 0 1 1 0 Recommendation V.26 bis [60]
0 1 0 1 1 1 Recommendation V.26 ter [61]
0 1 1 0 0 0 Recommendation V.27 [62]
0 1 1 0 0 1 Recommendation V.27 bis [63]
0 1 1 0 1 0 Recommendation V.27 ter [64]
0 1 1 0 1 1 Recommendation V.29 [65]
0 1 1 1 0 1 Recommendation V.32 [66]
1 0 0 0 0 0
through national use
1 0 1 1 1 1
1 1 0 0 0 0
through user specified
1 1 1 1 1 1
All other values reserved.
y) Mode duplex (octet 5d)
Bit
7
0 Half duplex
1 Full duplex
p2) User information layer 2 protocol (octet 6)
Bits
5 4 3 2 1
0 0 0 1 0 - Recommendation Q.921/I.441 [3]
0 0 1 1 0 - Recommendation X.25 [5], link layer
All other values are reserved.
NOTE 1 - If the transfer mode is "packet mode", octet 6 shall be present. For other cases, if the user layer 2 protocol is to be identified to the network, then octet 6 shall be present; otherwise octet 6 shall be omitted.
p3) User information layer 3 protocol (octet 7)
Bits
5 4 3 2 1
0 0 0 1 0 - Recommendation Q.931/I.451
0 0 1 1 0 - Recommendation X.25, packet layer
All other values are reserved.
NOTE 2 - If the user information layer 3 protocol is to be identified to the network, octet 7 shall be present; otherwise octet 7 shall be omitted.
| BC Attributes | Additional Attributes | ||||
|---|---|---|---|---|---|
| Transfer mode | Information transfer capability | Structure | Configuration | Establishment | Symmetry |
| Circuit | Speech | 8 kHz integrity | Point-to-point | Demand | Bi-directional symmetric |
Circuit Unrestricted data 8 kHz integrity Point-to-point Demand Bi-directional symmetric Circuit Restricted data 8 kHz integrity Point-to-point Demand Bi-directional symmetric Circuit 3,1 kHz audio 8 kHz integrity Point-to-point Demand Bi-directional symmetric Circuit Unrestricted data with tones/announcements 8 kHz integrity Point-to-point Demand Bi-directional symmetric Circuit Video 8 kHz integrity Point-to-point Demand Bi-directional symmetric Packet Unrestricted data Service data unit integrity Point-to-point Demand Bi-directional symmetric NOTES 1 When the information transfer rate 2x64 kbit/s is used, 8 kHz integrity with Restricted Differential Time Delay (RDTD) is offered. 2 When multirate (64 kbit/s base rate) is indicated as the information transfer rate, Time Slot Sequence integrity shall be provided.