4.3.1 Specifying D Channel CTA Context Streams and Timeslots
4.3.2 Specifying B Channel CTA Context Streams and Timeslots

4.4 Accessing D Channels

4.4.1 Initializing ISDN Protocol Stack Instances

4.5 Starting the "No Call Control" TCP

4.5.1 Setting mediamask (AG Quad T/E only)

4 Initializing a Messaging API Application

4.1 Introduction

This chapter:

Describes how to make MVIP switch connections (if necessary) to route D channel and B channel information to appropriate resources.

Shows how to initialize CT Access or AG Access, and create CTA contexts for B channels and D channels.

Explains how to initializes ISDN protocol stack instances on D channel CTA contexts.

Explains how to start the "no call control" Trunk Control Program (TCP) on B channel CTA contexts.

4.2 Making Switch Connections for AG ISDN

To allow an application access to ISDN channels, several MVIP switch connections must be made. In your AG configuration file, if EnableMvip=NO and DigitalMode=PRI, these settings are automatically made when the AG board boots. However, if EnableMvip=YES, the application must make these settings, using the CTA switching service or swish utility (CT Access) or SwitchPath function calls (AG Access).

The connections to be made are:

The streams and timeslots carrying D channel information to and from the HDLC controller must be connected to the streams and timeslots accessible by the ISDN protocol stack. These connections must be full duplex. They must be made before the ISDN protocol stack is initialized. (Initialization is described in section 4.4.1.)

The streams and timeslots carrying voice information to and from the trunk must be connected to the streams and timeslots carrying voice information to and from the DSP resources. The connections must be full duplex.

The following table shows the connections made by default when EnableMVIP=NO and DigitalMode=PRI.

Note: Connections are listed in MVIP 95 nomenclature unless otherwise specified.

Board	Default Connections
AG Quad T	Full duplex, between trunk voice information and DSP resources: Trunk A: 0:0..22 => 17:0..22, 16:0..22 => 1:0..22 Trunk B: 4:0..22 => 17:24..46, 16:24..46 => 5:0..22 Trunk C: 8:0..22 => 17:48..70, 16:48..70 => 9:0..22 Trunk D: 12:0..22 => 17:72..94, 16:72..94 => 13:0..22 Full duplex, between HDLC controller and signaling streams: Trunk A: 2:0 => 21:0, 20:0 => 3:0 Trunk B: 6:0 => 23:0, 22:0 => 7:0 Trunk C: 10:0 => 25:0, 24:0 => 11:0 Trunk D: 14:0 => 27:0, 26:0 => 15:0
AG Quad E	Full duplex, between trunk voice information and DSP resources: Trunk A: 0:0..29 => 17:0..29, 16:0..29 => 1:0..29 Trunk B: 4:0..29 => 17:30..59, 16:30..59 => 5:0..29 Trunk C: 8:0..29 => 17:60..89, 16:60..89 => 9:0..29 Trunk D: 12:0..29 => 17:90..119, 16:90..119 => 13:0..29 Full duplex, between HDLC controller and signaling streams: Trunk A: 2:0 => 21:0, 20:0 => 3:0 Trunk B: 6:0 => 23:0, 22:0 => 7:0 Trunk C: 10:0 => 25:0, 24:0 => 11:0 Trunk D: 14:0 => 27:0, 26:0 => 15:0
AG Quad Connect T	No DSP resource connections. Full duplex, between HDLC controller and signaling streams: Trunk A: 2:0 => 21:0, 20:0 => 3:0 Trunk B: 6:0 => 23:0, 22:0 => 7:0 Trunk C: 10:0 => 25:0, 24:0 => 11:0 Trunk D: 14:0 => 27:0, 26:0 => 15:0
AG Quad Connect E	No DSP resource connections. Full duplex, between HDLC controller and signaling streams: Trunk A: 2:0 => 21:0, 20:0 => 3:0 Trunk B: 6:0 => 23:0, 22:0 => 7:0 Trunk C: 10:0 => 25:0, 24:0 => 11:0 Trunk D: 14:0 => 27:0, 26:0 => 15:0
AG Dual T	Full duplex, between trunk voice information and DSP resources: Trunk A: 0:0..22 => 17:0..22, 16:0..22 => 1:0..22 Trunk B: 4:0..22 => 17:24..46, 16:24..46 => 5:0..22 Full duplex, between HDLC controller and signaling streams: Trunk A: 2:0 => 21:0, 20:0 => 3:0 Trunk B: 6:0 => 23:0, 22:0 => 7:0
AG Dual E	Full duplex, between trunk voice information and DSP resources: Trunk A: 0:0..29 => 17:0..29, 16:0..29 => 1:0..29 Trunk B: 4:0..29 => 17:30..59, 16:30..59 => 5:0..29 Full duplex, between HDLC controller and signaling streams: Trunk A: 2:0 => 21:0, 20:0 => 3:0 Trunk B: 6:0 => 23:0, 22:0 => 7:0
AG-T1	Full duplex, between trunk voice information and DSP resources: MVIP 95: 0:0..22 => 5:0..22, 4:0..22 => 1:0..22 MVIP 90: 16:0..22 <=> 18:0..22 Full duplex, between HDLC controller and signaling streams: MVIP 95: 2:0 => 9:0, 8:0 => 3:0 MVIP 90: 17:0 <=> 20:0
AG-E1	Full duplex, between trunk voice information and DSP resources: MVIP 95: 0:0..29 => 5:0..29, 4:0..29 => 1:0..29 MVIP 90: 16:0..29 <=> 18:0..29 Full duplex, between HDLC controller and signaling streams: MVIP 95: 2:0 => 9:0, 8:0 => 3:0 MVIP 90: 17:0 <=> 20:0

4.3 Initializing CT Access or AG Access

To begin operations, the application initializes CT Access or AG Access, and creates a separate CTA context for each D channel and B channel it will require. To accomplish this:

Under CT Access:

Under AG Access:

1. Initialize CT Access services (including the ISDN service and the ADI service), using ctaInitialize.

2. Create one or more event queues, using ctaCreateQueue. Each function call creates a queue and returns a handle. Make sure at least one queue is attached to the ADI service manager.

3. Create one or more contexts, using ctaCreateContext. Each call creates a CTA context and returns a CTA context handle.

4. Open services you initialized in step 1 on the CTA contexts using ctaOpenServices.

1. Open the AG driver using adiOpenDriver, and obtain a driver handle.

2. Open one or more CTA contexts, using adiOpenPort. Each CTA context is represented by a CTA context handle.

For more information about initializing CT Access, see the CT Access Developer's Reference Manual. For more information about initializing AG Access, see the AG Access Developer's Manual.

4.3.1 Specifying D Channel CTA Context Streams and Timeslots

Create a separate CTA context for each D channel that your application will interact with. The AG Quad T, AG Quad E, AG Quad Connect T, and AG Quad Connect E can each support up to four separate D channels. The AG Dual T and AG Dual E can each support up to two separate D channels. The AG-T1 and AG-E1 can support one D channel each.

To open CTA contexts under CT Access, use ctaCreateContext followed by ctaOpenServices. To open CTA contexts under AG Access, use adiOpenPort. In each call to ctaCreateContext or adiOpenPort, specify:

stream and timeslot - A base MVIP stream and timeslot.

mode - Specifies how many timeslots are allocated. For D channel contexts, set mode to 0, since no DSP processing resources are needed to control the D channel data stream.

Under CT Access, these values are included in the CTA_MVIP_ADDR structure passed to ctaCreateContext. Under AG Access, they are specified directly in the adiOpenPort.

4.3.2 Specifying B Channel CTA Context Streams and Timeslots

Along with your D channel contexts, create a separate CTA context for each B channel that your application will interact with. In each call to ctaCreateContext or adiOpenPort, specify:

stream - For B channel contexts, set stream to the voice stream(s) for the on-board DSPs. These streams are:

Board	DSP Resource Stream
AG-T1, AG-E1	MVIP 95: Local stream 4 MVIP 90: Stream 18
AG Quad T, AG Quad E, AG Dual T, AG Dual E	MVIP 95: Local stream 16
AG Quad Connect T, AG Quad Connect E	No on-board DSP resources

timeslot - For B channel contexts, set to a base timeslot in stream.

mode - For B channel contexts, set mode to ADI_VOICE_DUPLEX. This mode allows voice (inband) transmission and reception. Do not use the voice and signaling modes defined in the AG Access or ADI documentation, since the Channel Associated Signaling (CAS) connections are disabled in AG ISDN.

Under CT Access, these values are included in the CTA_MVIP_ADDR structure passed to ctaCreateContext. Under AG Access, they are specified directly in adiOpenPort.

4.4 Accessing D Channels

Once one or more CTA contexts have been created for the D channels, initialize a separate ISDN protocol stack instance for each of these CTA contexts, and associate a specific D channel with each one. When this is done, a D channel is ready to send and receive messages.

4.4.1 Initializing ISDN Protocol Stack Instances

Use isdnStartProtocol to initialize ISDN protocol stack instances.

Note: Once you call isdnStartProtocol, any CTA contexts you assign to D channels should be used only by the ISDN part of your application, and not in any other ADI calls.

To start up an ISDN protocol stack instance for ISDN ACU call control or LAPD, set the protocol, partner_equip, and parms arguments as follows:

protocol Set to:

- ISDN_PROTOCOL_Q931CC for ACU configuration, or

- ISDN_PROTOCOL_LAPD for LAPD configuration.

partner_equip
The type of equipment connected to the AG board. Set to one of the following:

If the AG board is...

And AG ISDN is to run in:

Set partner_equip to:

Connected to network

ACU configuration

EQUIPMENT_NT

Connected to network

LAPD configuration

EQUIPMENT_DCE

Acting as network

ACU configuration

EQUIPMENT_TE

Acting as network

LAPD configuration

EQUIPMENT_DTE

parms Pointer to a parameter structure to configure the protocol stack. If the application needs to change any of the parameters described in Appendix C: Parameters, pass a pointer to one of the following structures in this call:

- ISDN_PROTOCOL_PARMS_Q931CC for ACU configuration, or

- ISDN_PROTOCOL_PARMS_LAPD for LAPD configuration.

If the application will not need to modify parameters, pass NULL to accept the default settings. The default parameters for either configuration enable the required service access points (SAPIs). Furthermore, for ACU, all the services are supported by default.

The ISDNEVN_START_PROTOCOL event contains the completion status of the start request. If the ISDN protocol stack instance started successfully, the value field in this event will contain SUCCESS. Otherwise, another value will appear here.

For more information about isdnStartProtocol, see Chapter 7.

4.5 Starting the "No Call Control" TCP

Once all ISDN protocol stack instances have been created, start a "no call control" TCP on each B channel CTA context. This TCP puts the CTA context in a state where voice or media functions can be used without call control.

To start the TCP, call adiStartProtocol for each B channel CTA context, specifying NOCC in the protoname argument.

When adiStartProtocol is called, ADIEVN_STARTPROTOCOL_DONE is returned. If the NOCC TCP is started successfully, the event value field contains ADI_REASON_FINISHED. Otherwise, the value field contains another reason code.

4.5.1 Setting mediamask (AG Quad T/E only)

mediamask is a field in the ADI_CALLCTL_PARMS structure passed in the adiStartProtocol call. It controls which DSP resources are reserved for each DSP function (DTMF detection, echo cancellation, etc.). If you are using an AG Quad T or AG Quad E, you may need to change the setting of mediamask depending upon the setting of the CCMode statement in your AG configuration file. CCMode defines the call control resource allocation for these boards.

If CCMode = NONE, no resources are allocated for call processing. In this case, mediamask can be set to a non-zero value, but your application should not open more than 60 ports simultaneously. This is because AG Quad T and AG Quad E boards each have 60 DSP resources and can support up to 60 calls.

Set CCMode and mediamask this way if your application primarily performs switching (i.e. does not require heavy use of DSP resources).

If CCMode is set to HIGH, MEDIUM, or LOW, resources are allocated for call processing. In this case, mediamask must be set to zero. 120 ports then become available. Note, however, that only up to 60 ports can simultaneously use DSP resources.

Set CCMode and mediamask this way if your application requires heavy use of DSP resources (i.e. for interactive voice response or another such task).

If CCMode is set to HIGH, MEDIUM, or LOW and mediamask is non-zero, when adiStartProtocol is called, an ADIEVN_START_PROTOCOL_DONE event is returned with the value field set to ADIERR_NOT_ENOUGH_ RESOURCES.

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If the AG board is...	And AG ISDN is to run in:	Set partner_equip to:
Connected to network	ACU configuration	EQUIPMENT_NT
Connected to network	LAPD configuration	EQUIPMENT_DCE
Acting as network	ACU configuration	EQUIPMENT_TE
Acting as network	LAPD configuration	EQUIPMENT_DTE