Other Optional ISDN Configurations

Besides D channel backup and Information Elements, there are other optional configurations that are available with ISDN PRI.

ISDN cards support B channel negotiation on incoming calls as defined in Lucent TR41459 for both E1 and T1 cards. This feature allows the user receiving the incoming call (SETUP) to negotiate for the selection of the B channel. Only B channels controlled by the same D channel are considered for the selection procedure.

The SETUP message indicates the channel as either exclusive (does not accept an alternative) or preferred (any alternative is acceptable). If the channel is specified as preferred, but the user cannot grant the indicated channel, it selects any other B channel associated with the D channel. If the channel was specified as exclusive, no negotiation of the selection of the B channel is permitted and the call is rejected.

B channel negotiation is enabled using the ISDN Interface Configure message. The following selection modes are provided:

For NFAS, B channels on the same facility are selected before channels on other facilities.

The following example shows the use of the ISDN interface Configure message to select the B channel negotiation mode.

Byte	Field Description	Value and Indication
0	Frame	0xFE
1, 2	Length	0x000F (15)
3, 4	Message Type	0x0060
5	Reserved	0x00
6	Sequence Number	0x00
7	Logical Node ID	0x01
8	AIB Address Method	0x00 (Single Entity)
9	Number of Address Elements	0x01
10	Address Element Type	0x0D (Channel)
11	Address Data Length	0x03
12, 13	Address Data[0] Logical Span	0x0000 (Span 0)
14	Address Data[1] Channel	0x17 (Channel 23)
15	Entity	0x06 (B Channel Selection Mode)
16	Data[0] Reserved	0x00
17	Data[1]	0x01 (Linear Clockwise)
18	Checksum	0xCS (not shown in trace)

ISDN cards support the Automatic Number Identification (ANI) on Demand feature as specified in Lucent TR41459. This feature allows the host to request the Calling Party Number from networks that support ANI such as AT&T MultiQuest.

A PPL Event Request message of ANI on Demand (0x21) must be sent from the host immediately after receiving the Request For Service message from the CSP. If the call has already been answered, a NACK of 0xC0 is returned by the CSP.

If successful, a FACILITY message is sent to the network requesting the ANI. A PPL Event Indication message of FACILITY ACKNOWLEDGE is returned containing the ANI information in a Calling Party IE or Network-specific Facility IE. If the ANI is not supported by the network or is not available, a PPL Event Indication message of FACILITY REJECT is returned by the CSP.

The figure below shows a call flow using the PPL Event Request message to implement the ANI On Demand feature.

ISDN cards support the Vari-A-Bill feature as specified in Lucent TR41459. This feature allows the host to request a change in billing for an incoming call. You can use this feature after a call has been answered and only if the SETUP message indicates that the network supports the flexible billing service.

To enable Vari-a-Bill, send a PPL Event Request message with a PPL Event of Vari-A-Bill (0x20), specifying the new billing information in a Vari-A-Bill Data ICB (0x12). The CSP sends a FACILITY message to the network requesting the billing change.

If the call is not in the answered state, then the feature is not supported and a NACK of 0xC0 is returned by the CSP. A PPL Event Indication of FACILITY is returned from the network indicating whether the billing change was successful. See the Lucent TR41459 specification for detailed information.

The following call flow shows the use of the PPL Event Request message to implement the Vari-A-Bill feature.

The following example shows the PPL Event Request message to implement Vari-A-Bill billing and change the billing rate.

Trace X->H FE [00 1E] [00 44] 00 00 01 00 01 0D 03 00 00 00 [00 05] 00 20 01 02 10 0A 01 12 07 01 90 30 31 32 35 36

Name for the data fields within an ISDN Layer 3 message. See Integrated Services Digital Network.

See Integrated Services Digital Network.

See Automatic Number Identification.

Bearer channel, 64Kbps (ISDN) The channel that carries the actual payload (as opposed to D-channels, which carry signaling data that helps route the payload).

A digital communications link - voice, data, and video at a 2.048 Mbps rate; 30B/2D or 31B/1D (ISDN); non-North American version of T1.

Digital communications link - voice, data, and video at a 1.544 Mbps rate (24 64 Kbps channels)

See Non Facility Associated Signaling.

A group of data bits in a specific format, with a flag at each end to indicate the beginning and the end of the frame.

See Address Information Block.

The information in an AIB that follows the header, down to the data field. An AIB can have one or more Address Elements. AEs correspond to Span, Channel, and SS7 Link.

Range of channels provided by T1 or E1 transmission service. A physical span is a group of channels taking up a single physical wire. A logical span is a group of channels taking up less than a single logical wire, or carried over more than one physical wire.

ANI. This feature allows a host to request the call originating number (calling party number) from networks that support Automatic Number Identification such as AT&T MultiQuest.

See Programmable Protocol Language.

RFS. A Status Message indicating that some entity is requesting service from the Excel platform.

Negative acknowledgement to a message.

A condition that, when met, drives a state machine from one state to another. A condition that drives a Component out of its current state by invoking an associated primitive.

See Information Control Block.

A programmable software component that uses PPL state machines that can be modified with the PPL Tool.