1.1 Introduction

1.2 Telephone Trunks

1.2.1 Analog Trunks

1.2.2 Digital Trunks

1.3 Trunk Interface Boards

1.3.1 Trunk Interface Boards and the MVIP Bus

1.4 CAS Protocol Software

1.5 Protocols and Natural Access

1.5.1 Trunk Control Programs (TCPs)

1.5.2 Parameter Files

1.6 Protocol Software Package Contents

1.6.1 Trunk Control Programs (TCPs)

1.6.2 Configuration and Parameter Files

1.6.3 Binary Parameter Category Definition Files

Binary Parameter File Backups

1.6.4 ASCII Parameter Value Definition Files

1.6.5 SLAC Files

1.1 Introduction

The NMS CAS for Natural Call Control Developer's Manual describes how to install and run NMS Channel Associated Signaling (CAS) protocol software with the NCC service. The manual also describes how to build CAS protocol call control applications using the Natural Access application programming interface, and NCC service call control functions.

NMS CAS protocols include:

• Analog Loop Start (LPS)

• Australian P2 (AP2)

• European Digital CAS (EUC)

• Feature Group D (FGD)

• Ground Start (GDS)

• MF-Socotel (MFS)

• Multi-Frequency Compelled R2 (MFC)

• Off-Premises Station (OPS)

• Operator Work Station (STA)

• Pulsed E & M (EAM)

• Signaling System 5 (SS5)

• System R1.5 (R15)

• Wink Start (WNK)

This manual is targeted to developers of telephony and voice applications who are using Natural Access. This document defines telephony terms where applicable, but assumes that the reader is familiar with telephony concepts and switching. It also assumes that the user is familiar with the C programming language.

Note: The Natural Call Control (NCC) service API is the new standard call control API for NMS products. The NCC service provides an extended and enhanced version of the call control portion of the ADI service API. If your application currently uses the ADI service for call control, consider migrating to the NCC service for better performance, new features, and more control over your application's call control functionality.

Refer to the Natural Call Control Service Developer's Reference Manual for further information.

This chapter:

• Summarizes analog loop start and digital T1 and E1 trunks.

• Explains how NMS boards are used in computer telephony applications.

• Discusses protocol software, and its role in a computer telephony application.

• Lists and describes the other software components required in a computer telephony application.

• Provides broad outlines for developing computer telephony applications that use CAS protocols.

1.2 Telephone Trunks

This section describes the types of line interface boards used to connect to telephone networks.

1.2.1 Analog Trunks

Analog trunks with loop start signaling are the most common type of telephone trunks found in residential installations. The network uses the presence or absence of current flow in the telephone circuit as signaling information when establishing and processing connections.

1.2.2 Digital Trunks

Digital trunks multiplex the signal of many different channels into one interface. Digital trunks follow two basic standards around the world:

• T1 trunk lines have a capacity of 1.544 Mbps, and typically handle 24 simultaneous telephone channels. T1 trunks are used in the United States, Canada, Hong Kong, and Japan.

• E1 trunk lines have a capacity of 2.048 Mbps and typically handle 30 simultaneous telephone channels. E1 trunks are used mainly in Europe, Asia, and South America.

Digital trunks use signaling bits associated with voice channels to carry signaling information. For a detailed description of T1 and E1 communications, see the appropriate board installation and developer's manual.

1.3 Trunk Interface Boards

NMS provides a variety of trunk interface boards for connecting to public switched telephone networks (PSTNs). The boards discussed in this manual include NMS AG and CG board families.

1.3.1 Trunk Interface Boards and the MVIP Bus

NMS trunk interface boards can connect to other boards in the same chassis over the CT bus. The CT bus is a high-speed, time-division multiplexed digital telephony bus between telephone line interface boards (such as AG 2000 and AG Quad boards), that allows boards to share data, signaling, and switching information. You can add additional DSP resources, analog line interfaces, or loop start line interfaces, by using other AG 2000 and Quad boards or board sets.

You can also use MVIP-compatible products from other manufacturers with NMS boards.

For detailed information about a particular NMS board, refer to the appropriate board installation and developer's manual.

WARNING:

Natural MicroSystems obtains board-level approval certificates for supported countries. Some countries require that you obtain system-level approvals before connecting a system to the public telephone network. To learn what approvals you require, contact the appropriate regulatory authority in the target country.

1.4 CAS Protocol Software

To communicate across a trunk line, parties must signal one another. The scheme used to signal across a telephone line is called a protocol. Many different protocol standards are in use throughout the world.

The NMS CAS package includes:

• Analog Loop Start protocols (LPS)
  This protocol family includes protocols that use loop start signaling, where the presence or absence of current flow is interpreted by a switch as protocol signaling events.

• Australian P2 protocols (AP2)
  This protocol is used in Australia for connections between PBX's and some PSTN carriers. It uses two-bit line signaling (derived from CCITT recommendation Q.421), and in-band DTMF register signaling.

• European Digital Channel Associated Signaling protocol (EUC)
  This protocol family includes channel associated signaling protocols used in certain European countries. The protocols use two-bit line signaling specified by national standards for use over E1 trunks. The register signaling is either carried by in-band DTMF tones (not compelled) or by out-of-band decadic pulses.

• Feature Group D protocols (FGD)
  The FGD protocol implements the specifications of the Feature Group D (FGD) switched access service. This service provides interconnection to the BOC (Bell Operating Companies) network for the provision of message telecommunications service/wide area telecommunications service (MTS/WATS) and MTS/WATS-type services. FGD service, which provides access to the trunk side of suitably equipped BOC switching systems, is available for termination and originating access.

• Ground Start protocol (GDS)
  Natural MicroSystems ground start protocols cover digital interfaces (T1 trunks) connected to a private branch exchange (PBX) or PSTN switches. The protocol can handle two signaling variations: FX (foreign exchange) and SA (special access).

• MF-Socotel protocol (MFS)
  This protocol conforms to the Spanish National Specifications for Channel Associated Signaling over E1 trunks. It uses single bit steady-state line signaling and MF-Socotel MF compelled in-band register signaling.

• Multi-Frequency Compelled protocols based on the R2 standard (MFC)
  This protocol family includes the CCITT Signaling System R2 (Recommendations Q.421 to Q.442, CCITT Blue Book, 1988) implementation and numerous national variations. These protocols run on E1 trunks and use two-bit line signaling on the signaling channel associated with each voice channel and in-band MF compelled register signaling.

• Off-Premises Station protocols (OPS)
  The Natural MicroSystems OPS protocol covers only digital interfaces. The protocol can handle T1 or E1 digital trunks, of signaling types FX (foreign exchange) or SA (special access).

• Operator Workstation protocol (STA)
  This protocol is the other side of the analog loopstart protocol. It is used to implement stations that connect to analog phones.

• Pulsed E & M protocol (EAM)
  This protocol family includes country-specific protocols that use one-bit line signaling in a pulsed form, and variations on the compelled in-band MF register signaling specified by the CCITT in the 1988 Blue Book. These protocols run on E1 trunks and are specified in different countries by national regulatory agencies.

• Signaling System 5 protocol (SS5)
  This protocol is specified by the CCITT Recommendations Q.140 to Q.154 (CCITT Red Book, Volume VI Fascicle VI.2, Geneva 1985). The protocol uses in-band compelled signal frequency tones to perform line signaling and in-band MF tones for register signaling. Since no signaling bits are used, this protocol works the same way on T1 and E1 trunks.

• System R1.5 protocols (R15)
  This protocol family includes channel associated signaling protocols used for E1 lines in Russia (based on CCITT recommendations Q.511 and Q.544). The protocols use two-bit steady-state line signaling. Register signaling is either carried by in-band MF tones (MF acknowledged pulses) or by out-of-band decadic pulses. Two R15 protocol software modules are included with the NMS CAS software package. One is used (r150) for controlling inbound calls and the other (r151) is used for controlling outbound calls.

• Digital and Analog Wink Start protocol (WNK)
  This protocol family includes protocols used on T1 in the USA, Hong Kong, and Taiwan. The protocol uses one-bit signaling, two-bit signaling, or presence or absence of current, and owes its name to the wink (brief presence of current or variation of the signaling bit) that the inbound side uses to acknowledge line seizure. Register signaling is performed by in-band DTMF or MF tones, or by out-of-band decadic pulses.

Most of the protocols in these families have country-specific variations. NMS provides parameter files that determine how protocols interact with telephone networks in different countries. The package for each country contains software modules you need to download to enable telephony boards to communicate with telephone networks in that country.

1.5 Protocols and Natural Access

Natural Access is a development environment providing standard programming interfaces for telephony functions that are hardware-independent. Within Natural Access, logically related telephony functions are subdivided into groups, or services. Call control is one such group. The service responsible for call control under Natural Access is called the Natural Call Control (NCC) service.

1.5.1 Trunk Control Programs (TCPs)

The NCC service provides a powerful call control API that allows an application to establish inbound or outbound calls and perform call transfer, blocking, and other operations. To keep this API relatively simple and
protocol-independent, the actual communication with the trunk is performed by another software entity, called a trunk control program (TCP). The TCP translates commands from the NCC service into signaling appropriate for the particular protocol running on the trunk, and translates protocol-specific trunk events into NCC service events (see Figure 1).

Figure 1. The TCP's Role in an Application

One or more TCPs is provided for each protocol. You load the TCP into the on-board memory of a line interface board. For applications that must simultaneously support multiple protocols and/or protocol variations, more than one TCP can be loaded to the telephony board at the same time. Each line supports one TCP at a time.

The TCPs to be loaded for an application are specified in the configuration file (described in Section 2.1). When you run your board configuration utility, it downloads the specified TCPs to the board. For more information about configuring your board(s), see the board-specific installation and developer's manual.

1.5.2 Parameter Files

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), each of which programs the TCP for a particular country or network variation. Natural Access applications load these parameters automatically at initialization time.

The majority of the parameters specified in TCP parameter files cannot be changed without violating national regulatory laws. However, you can change a subset of these parameters based on the needs of your application. For more information about loading parameters, refer to Chapter 3. For information about parameters for each protocol, refer to Chapter 5 through Chapter 17.

WARNING:

You may only change a subset of parameters for each CAS protocol without affecting regulatory approvals. Chapter 5 through Chapter 17 list all parameters for each protocol and indicate which parameters may be edited. Editing other parameters may result in violations of country-specific regulations.

1.6 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)

• Four country-specific binary parameter files

• Four editable (ASCII) country-specific parameter files

• Sample country-specific configuration files

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

Each installed protocol includes all of these components. When you install multiple protocols or install protocols for multiple countries, several versions of each component are created.

Note: To ensure backwards compatibility, the NMS CAS for NCC software package contains components to support NMS CAS protocols for the ADI service. For this reason, the NMS CAS for NCC protocols package contains a binary parameter file and an editable parameter file for ADI service functionality. These files (adiprt.pf and adiprt.par) are not used by the NCC service.

Natural Access includes several call control demonstration programs that can use any of the NMS CAS protocols to place or receive calls. Refer to the Natural Call Control Service Developer's Reference Manual for more information about running these programs.

1.6.1 Trunk Control Programs (TCPs)

CAS TCPs include the following:

Protocol	File name
Analog Loop Start	lps0.tcp
Australian P2	ap20.tcp
European Digital CAS	euc0.tcp
Feature Group D	fgd0.tcp
Ground Start	gds0.tcp
MF-Socotel	mfs0.tcp
Multi-Frequency Compelled R2	mfc0.tcp
Off-Premises Station	ops0.tcp
Operator Workstation	sta0.tcp
Pulsed E and M	eam0.tcp
Signaling System 5	ss50.tcp
System R1.5	r150.tcp, r151.tcp
Wink Start (Digital and Analog)	wnkx (x=0,1)

1.6.2 Configuration and Parameter Files

Configuration files contain information that determines how your configuration utility sets up boards. These files also contain country-specific information for different protocols.

Examples of Natural Access 4.0 configuration files are listed in the following table (where prt indicates the protocol and cty indicates the country where used):

File name	Location	Description
qpiprt.cfg	Windows: \nms\ag\cfg UNIX: /opt/nms/ag/cfg	Default example configuration file to configure one board with all the modules and settings to run protocol prt. It reflects the last country installed in the system for the protocol prt. For AG Quad and Dual T1 and AG Quad and Dual E1.
qpiprtcty.cfg	Windows: \nms\ag\cfg\country UNIX: /opt/nms/ag/cfg/country	Example configuration file to configure one board with all the modules and settings to run protocol prt in the country cty. A different file is installed for each country. For AG Quad and Dual T1 and AG Quad and Dual E1.
a4piprt.cfg	Windows: \nms\ag\cfg UNIX: /opt/nms/ag/cfg	Default example configuration file to configure one board with all the modules and settings to run protocol prt. It reflects the last country installed in the system for the protocol prt. For AG 4000 boards.
a4piprtcty.cfg	Windows: \nms\ag\cfg\country UNIX: /opt/nms/ag/cfg/country	Example configuration file to configure one board with all the modules and settings to run the protocol prt in the country cty. A different file is installed for each country. For AG 4000 boards.
a2piprt.cfg	Windows: \nms\ag\cfg UNIX: /opt/nms/ag/cfg	Default example configuration file to configure one board with all the modules and settings to run protocol prt. It reflects the last country installed in the system for the protocol prt. For AG 2000 boards.
a2piprtcty.cfg	Windows: \nms\ag\cfg\country UNIX: /opt/nms/ag/cfg/country	Example configuration file to configure one board with all the modules and settings to run the protocol prt in the country cty. A different file is installed for each country. For AG 2000 boards.
c6prtcty.cfg	Windows: \nms\cg\cfg\country UNIX: /opt/nms/cg/cfg/country	Example CG configuration file to configure one board with all the modules and settings to run the protocol prt in the country cty. A different file is installed for each country. For CG 6000C boards.

Examples of Natural Access 3.0 configuration files are listed in the following table (where prt indicates the protocol and cty indicates the country where used):

File name	Location	Description
agprt.cfg	Windows: \nms\ag\cfg UNIX: /opt/nms/ag/cfg	Default example configuration file to configure one board with all the modules and settings to run protocol prt. It reflects the last country installed in the system for the protocol prt. For AG-8, AG-T1, AG-E1, AG 2000.
agprtcty.cfg	Windows: \nms\ag\cfg\country UNIX: /opt/nms/ag/cfg/country	Example configuration file to configure one board with all the modules and settings to run protocol prt in the country cty. A different file is installed for each country. For AG-8, AG-T1, AG-E1, AG 2000.
qprt.cfg	Windows: \nms\ag\cfg UNIX: /opt/nms/ag/cfg	Default example configuration file to configure one board with all the modules and settings to run protocol prt. It reflects the last country installed in the system for the protocol prt. For AG Quad and Dual T1 and AG Quad and Dual E1.
qprtcty.cfg	Windows: \nms\ag\cfg\country UNIX: /opt/nms/ag/cfg/country	Example configuration file to configure one board with all the modules and settings to run protocol prt in the country cty. A different file is installed for each country. For AG Quad and Dual T1 and AG Quad and Dual E1.
a4prt.cfg	Windows: \nms\ag\cfg UNIX: /opt/nms/ag/cfg	Default example configuration file to configure one board with all the modules and settings to run protocol prt. It reflects the last country installed in the system for the protocol prt. For AG 4000 boards.
a4prtcty.cfg	Windows: \nms\ag\cfg\country UNIX: /opt/nms/ag/cfg/country	Example configuration file to configure one board with all the modules and settings to run the protocol prt in the country cty. A different file is installed for each country. For AG 4000 boards.

For more information about configuration files, refer to Chapter 2 of this manual and the appropriate board installation and developer's manual. For Natural Access 4.0 or later, also refer to the NMS OAM System Users Manual. For Natural Access 3.0 or earlier, refer to the AG Runtime Configuration and Developer's Manual.

1.6.3 Binary Parameter Category Definition Files

Binary parameter files contain the complete set of country-specific parameters and default values. These files are loaded by Natural Access at initialization time. There are four types of binary parameter category definition files (where prt indicates the protocol and cty indicates the country where used):

File name	Location	Description
nccxprt.pf	Windows: \nms\ag\cfg UNIX: /opt/nms/ag/cfg	Defines the Natural Access parameter category NCC.X.ADI_prt. This category holds all protocol-specific parameters for the prt protocol. The parameter default values defined by these files apply to the TCP implementing the protocol prt for the last country installed.
nccxadi.pf	Windows: \nms\ag\cfg\ UNIX /opt/nms/ag/cfg	Defines the Natural Access parameter category NNC.X.ADI_START and NCC.X.ADI_PLACECALL. These parameter categories include all the country-specific parameters for boards in the AG family.
nccstart.pf	Windows: \nms\ag\cfg UNIX: /opt/nms/ag/cfg	Defines the Natural Access parameter category NCC.START. NCC.START parameters include all of the country-specific parameters for the last country installed.
adiprt.pf	Windows: \nms\ag\cfg UNIX: /opt/nms/ag/cfg	Provides for backwards compatibility for applications that use the ADI service for call control. It defines the Natural Access parameter category ADIprt which contains all the protocol-specific parameters for the prt protocol. The parameter default values defined by these files apply to the TCP implementing the protocol prt for the last country installed.

Note: Installing another country variation of a specific protocol overwrites the nccxprt.pf and adiprt.pf files.

Binary Parameter File Backups

When you install NMS CAS for Natural Call Control software, the installation program installs backup copies of binary parameter files.The following table provides the names and locations of these backup files (where prt indicates the protocol and cty indicates the country where used):

Binary parameter file	Backup file	Backup file location
nccxprt.pf	nccxprtcty.pf	Windows: \nms\ag\cfg\country UNIX: /opt/nms/ag/cfg/country
nccxadi.pf	nccxadicty.pf	Windows: \nms\ag\cfg\country UNIX: /opt/nms/ag/cfg/country
nccstart.pf	nccstartcty.pf	Windows: \nms\ag\cfg\country UNIX: /opt/nms/ag/cfg/country
adiprt.pf	prtcty.pf	Windows: \nms\ag\cfg\country UNIX: /opt/nms/ag/cfg/country

1.6.4 ASCII Parameter Value Definition Files

ASCII parameter value definition files can be used to reset the values of the country specific parameters. Some of the parameters values may be changed without affecting the regulatory approvals in the target country.

These files can be used to set the parameter values system-wide, using the CT daemon, or it can be parsed by the application for dynamic parameter management with Natural Access functions.

Parameters within the ASCI parameter files fall within two classes:

• Those that can be changed by the user to fit the application's needs

• Those that should not be changed because they have regulatory relevance.

There are four types of ASCII parameter value definition files:

File name	Location	Description
nccxprt.par	Windows: \nms\ctaccess\cfg UNIX: /opt/nms/ctaccess/cfg	Defines the Natural Access parameter category NCC.X.ADI_prt. This category holds all protocol-specific parameters for the prt protocol. The parameter default values defined by these files apply to the TCP implementing the protocol prt for the last country installed.
nccxadi.par	Windows: \nms\ctaccess\cfg\ UNIX: /opt/nms/ctaccess/cfg	Defines the Natural Access parameter category NNC.X.ADI_START and NCC.X.ADI_PLACECALL. These parameter categories include all of the country-specific parameters for boards in the AG family.
nccstart.par	Windows: \nms\ctaccess\cfg UNIX: /opt/nms/ctaccess/cfg	Defines the Natural Access parameter category NCC.START. NCC.START parameters include all of the country-specific parameters for the last country installed.

Note: Installing another country variation of a specific protocol overwrites the nccxprt.par and adiprt.par files.

Backups of ASCII parameter files are kept in the \nms\ctaccess\cfg\country (under Windows NT or Windows 2000) or /opt/nms/ctaccess/cfg/country (under UNIX) directory. These files are named in the same way as the binary file backup files, except that the file name includes a three letter string cty that specifies the country where used.

For more information about editable parameters for each CAS protocol, refer to Chapter 5 through Chapter 17.

1.6.5 SLAC Files

SLAC files contain information that must be loaded into the QSLAC devices of AG 2000 boards so that the board line interface is appropriate for country-specific line conditions.

For more information about the SLAC files, refer to the AG 2000 Installation and Developer Manual. Refer to Appendix D for the list of SLAC files available for different countries.

File name	Location	Description
ppctyssi.slc	Windows: \nms\ag\load UNIX: /opt/nms/ag/load	Programs the QSLAC devices on pp boards to implement the analog specifications of country cty, for the signaling protocol ss and with a line impedance i. Only one file per configuration is installed. SLAC files are referenced by the configuration files installed for the signaling protocol ss in country cty.