# CAS API software

This topic describes:

- Trunk control programs (TCPs)

- Country and network variations

- Protocol software package contents

- Available SLAC files

## Trunk control programs (TCPs)

The NaturalAccess NaturalCallControl API (NCC API) enables an application to establish inbound or outbound calls and to perform call transfer, blocking, and other operations. To keep this API relatively simple and protocol-independent, the communication with the trunk is performed by another software entity called a trunk control program (TCP). The TCP translates commands from the NCC API into channel associated signaling (CAS) appropriate for the particular protocol running on the trunk, and translates protocol-specific trunk events into NCC API events.

The following illustration shows the TCP's role in an application:

CAS API software provides a series TCPs for a variety of protocols. The TCP is loaded into the on-board memory of a line interface board when you configure the board. For applications that must support multiple protocols and/or protocol variations simultaneously, more than one TCP can be loaded to the telephony board at the same time. Each line supports one TCP at a time.

For more information, refer to Configuring the boards.

## Country and network variations

Each country uses its own variation of a protocol. In addition to the basic TCP software, each protocol software package contains several binary parameter files (.pf files) that program the protocol for a particular country or network variation. NaturalAccess applications automatically load these parameters at initialization time.

For more information about loading parameters, refer to CAS setup tasks.

Warning: | You can change only a subset of parameters for each CAS protocol without affecting regulatory approvals. Editing other parameters may result in violations of country-specific regulations. For information about what parameters you can and cannot edit for a specific protocol, refer to the protocol topics in this document.

## Protocol software package contents

The software package for a given country-specific protocol includes:

- readme file (common for all protocols and countries)

- One or more trunk control programs (TCPs)

- Sample country-specific configuration files

- Four country-specific binary parameter files

- Four editable (ASCII) country-specific parameter files

- One or more SLAC files (for AG 2000 boards)

When you install multiple protocols or install protocols for multiple countries, several versions of each component are created. For more information on the installed components for a protocol, refer to CAS setup tasks.

NaturalAccess includes several call control demonstration programs that can use any of the CAS API protocols to place or receive calls. Refer to the Dialogic® NaturalAccess™ NaturalCallControl™ API Developer’s Manual for information about running these programs.

## Available SLAC Files

The following SLAC files are available under NCC:

File | Country | Signaling module | Line impedance, ohm | Termination impedance, ohm | Use
a2eurlsc.slc | Australia | Loop start/ CTR21 | 270 + (750 || 150nF) | 270 + (750 || 150nF) | Default
a2usals6.slc | North America | Loop start/US | 600+ 2.16uF | 600+ 2.16uF | Tests, PBX, default
a2usals9.slc | North America | Loop start/US | 900 | 600+ 2.16uF | PBX
a2usalsn.slc | North America | Loop start/US | (800//0.005uF) + 100 | 600+ 2.16uF | Unloaded loops
a2eurlsc.slc | Europe | Loop start/ CTR21 | 270 + (750 || 150nF) | 270 + (750 || 150nF) | Default
a2jpnls6.slc | Japan | Loop start/US | 600+ 2.16uF | 600+ 2.16uF | Tests, PBX, default
a2jpnls9.slc | Japan | Loop start/US | 900 | 600+ 2.16uF | PBX
a2jpnlsn.slc | Japan | Loop start/US | (800//0.005uF) + 100 | 600+ 2.16uF | Unloaded loops
a2canls6.slc | Canada | Loop start/US | 600+ 2.16uF | 600+ 2.16uF | Tests, PBX, default
a2canls9.slc | Canada | Loop start/US | 900 | 600+ 2.16uF | PBX
a2canlsn.slc | Canada | Loop start/US | (800//0.005uF) + 100 | 600+ 2.16uF | Unloaded loops

Note: For the purposes of this table, Europe includes Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Liechtenstein, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, and Switzerland.