Basic CTI services

The starting point for all CTI development is a set of basic services, which include call control, call monitoring, and feature activation. There are two recognized industry standards (CSTA (computer supported telecommunication applications) and SCAI (switch to computer applications interface)) for performing these functions as well as several dozen proprietary designs.

Call control

Switching software is the core technology enabling CTI to provide an outside application with some form of control over switch functions. The outside application is offered or can access a set of commands; for example, make call, answer call, and transfer call. When a command is issued, the switch tries to complete its assigned task and reports back to the application with a result. That result might mean complete success (the call went through), progress has been made (the other end is now ringing), or failure (the dialed number is busy or goes unanswered). This information has to be provided on a real time basis as events occur. The application design must allow for communications situations that occur in real life in call centers, such as peak times when all the lines are busy or power users who switch back and forth between several calls on hold. Users have come to expect almost instantaneous response times from their telephone systems; the CTI application designer must now deliver on that expectation. In this simple model, call control expects the application to act as if it were a telephone set (anything that a telephone could do, the application can now do). By extending that model to include the features of a modern business telephone (multiline, speed call, displays, etc.), the power of this basic service becomes apparent.

There are two approaches to call control:

§  First-party call control

§  Third-party call control

First-party call control

The basic premise of first-party call control is that the CTI application is acting on behalf of one user. In this model, the application is running on the user's desktop PC, and there is an actual physical connection between the application, the user's PC, and the user's telephone line. Through an application, the user can control the telephone call. Examples of these applications include the following:

§  Personal directory

§  Personal organizer

§  Personal answering machine

§  Personal call accounting

Third-party call control

The basic premise of third-party call control is that the CTI application acts on behalf of any of the clients in a workgroup or department. In this model, the application is running on a shared server and there is no direct physical connection between the user's PC and the telephone line. Instead, there is a "logical" connection: The user's PC application communicates with the server, which in turn controls the switch. The server provides a coordination point for all calls being handled in the workgroup. This makes possible a much more powerful (or useful) level of call control. The central server-based application can handle the distribution of all calls to the members of the workgroup, including activities like call screening or back-up answering. This has been a key element in the application of CTI—the potential for breakthrough productivity gains when used in high-performance workgroups.

Call monitoring

Both of the call control models described previously expect the application to act like a telephone. This is helpful in explaining call control, but it clearly ignores the range of capabilities of a PC. Recognizing this, the designers of CTI built in services, such as call monitors, that capitalize on the strengths of the PC.

The application can set a call monitor in the PBX (private business exchange) to collect information on almost any activity. For example, by setting a monitor on a single user's telephone set, the application can watch every button pushed, every digit dialed, every picking up or replacing of the handset. Similarly, by monitoring any trunk, the application can see each incoming call, collect ANI or DNIS data, watch where the call was directed, and know when and where it was answered. By selectively monitoring telephones, groups of telephones, or trunks, the application can get as detailed a picture of the PBX activities as required to make the application work. This is especially valuable in generating management reporting and performance measurement statistics.

Feature activation

The last of the basic CTI services described in this section is feature activation. Modern PBX systems provide over 200 features to improve call handling, although the majority of users never use more than 4 of them. The use of PC-based applications (which can be set to the user's preferences) unlocks the power already built into the telephone system by allowing simple computer screen-based control of features, such as arranging a conference call by clicking on the names of the parties involved.

In this application, commands are provided that activate, suspend, or turn off features within the switch. For example, the personal organizer application could set up call forwarding for a user who is away from the office and turn off the same call forwarding when the user returns. Similarly, a CTI application could modify call screening by a secretary on behalf of a workgroup. It would be turned off at the end of the business day and the calls would be automatically redirected to an answering service.

Telecom switching systems

The following elements are found in all telecom switching systems:

§  Operating system software that controls the hardware

§  Call processing software that makes connections, provides features, and delivers services

§  Line side interfaces connecting the switch to the end-user telephone set

§  Trunk side interfaces connecting the customer's switch to the network

§  A switching fabric linking the various interfaces

Operating system software

In the telecommunications environment as in the world of computing, hardware is controlled by operating system software. The telecom environment has special needs for multiuser, real-time, fault-tolerant operating systems. The complexities of the features available have resulted in switch products that use proprietary operating systems, a parallel to the proprietary legacy systems of the computing environment.

Call processing applications

The heart of a modern switching system is a set of software applications known collectively as call processing. This software provides all the functionality seen by the user—from the basic call setup to delivering caller ID. This software also provides user features (such as call forwarding), enhanced network services (such as least-cost routing), and specialized call handling for call centers. Call processing is the basis for powerful CTI applications that can make a call center highly effective and productive.

Interfacing hardware

Modern telecom systems operate by converting analog voice signals into a digital format known as pulse code modulation (PCM). The digital format is far superior for clear transmission, storage, compression, and even encryption. This process is accomplished by a silicon chip, a CODEC (for code and decode) designed into the line interface. The CODEC samples the voice signal 8000 times per second and transforms it into the digital signal, ready for transmission. At the other end, another CODEC chip transforms the digital signal into a recognizable voice signal.

The switching device performs the function of connecting the digital signal from the line interface to the destination, which might be another line interface (intercom call), a trunk interface (network call), or a common resource (such as a conference bridge). Once established, the connection stays up for the duration of the call. The trunk interface is a shared pipe into the public network. There are various types of trunk interfaces, defined by their bandwidth capacities—T1, T2, T3. For example, a single T1 trunk provides 24 circuit paths for digitized voice as well as the signaling to access the network services. Typically, these 24 circuits can provide service to about 150 users.

Network structures and CTI servers

A network structure is made up of several components—client computers and servers consisting of transport mechanisms—forming a physical interface and network architecture. Some examples of network architectures are Ethernet, 10BASE-T, Token Ring, and ATM (asynchronous transfer mode). A communications protocol (TCP/IP or SPX/IPX (sequenced packeteXchange/internetwork packeteXchange)) is also required to link the elements of a network. Each PC on the network has a LAN card to provide an interface to the network.

The server is a device that empowers the network and the attached users. There are several types of servers in LAN environments: file and print servers, departmental database servers, and legacy hosts acting as database servers. CTI introduces a new class of servers to the LAN infrastructure—telephony servers. (see Figure 1) Server platforms generally consist of the same basic hardware as the desktop PC but have some differences in operating characteristics. Generally, they are faster, more powerful, and have much more memory and disk space. They come in a variety of configurations and levels of robustness, depending on their intended use and the importance of maintaining data integrity or network connections. Telecom servers are a special class of telephony servers that deliver high bandwidth and require higher-capacity buses. These devices are described in more detail later in this chapter. (see Figure 2)

Figure 2.5: LAN server architecture.

Figure 2.6: Telecom server architecture.

As the LAN industry matured, developers started designing network-based applications that could be used in a network environment by many clients simultaneously. These applications are tolerant of delays imposed by multiuser access and led to the development of network operating systems: Novell NetWare, IBM LAN Manager, and Microsoft MS Windows NT.

Communications in the call center

There are a number of different telephone operating models, all of which may have a role in call center operations. The communications environment chosen for a call center will be related to the call volumes anticipated, number of seats in the center, and the geographical extent and coverage of the call center. Two of the most popular communication models are described in this section:

§  Public network

§  Customer premise

Public network model

The most important telephony elements related to CTI are services provided by public telephone networks and the capabilities of call processing and call control. The world's public telephone networks are complex, with millions of endpoints hard-wired and connected through thousands of central connecting points called central offices (COs). The public network has evolved over the years from its POTS (plain old telephone service) analog beginnings to the broad range of advanced, sophisticated services provided by today's digital technology. (see Figure 3)

Figure 2.7: Routing calls in the network.

The public network model has relatively simple communications architecture. Users with a "terminal device," such as a telephone, are connected by the network to a service provider—actually, a server. Once connected, the user can ask for any of the wide range of services generally available—from dialing a number to directory assistance or voice messaging. In general, the network operator or service provider can change or enhance capabilities without disrupting existing services. This model is present in many telecommunications environments. As a terminal device, a telephone handset has many variations. It may be analog or digital, with buttons and displays, and it can also be wireless. Terminal devices also include fax machines, modems, video phones, alarm systems, WAN equipment, and multimedia boards for PCs. Broadly defined, a terminal device is "any piece of hardware attached to the network, and capable of accessing the service provider."

The basic network infrastructure resembles a giant spider web, consisting as it does of a set of switches (the central offices referred to previously) interconnected by a variety of transmission media—fiber-optic cable, satellites, radio, underwater cables, and so on. In the public network circuit-switched service, a call is connected across the network and travels a number of different paths to get to its destination. The most basic service is the telephone call. The sequence of events is as follows:

§  The user picks up the phone (goes off-hook), which gets the attention of the network.

§  The user then dials a string of digits (which the network recognizes as an address).

Hidden from the user is all the logic for routing the call through the network, handling exceptions (such as routing invalid numbers to a recording), or invoking special features. This logic is delivered by a service provider attached somewhere within the network—again invisible to the user, other than through prerecorded messages.

In the public network, along with basic call-handling services there are a range of supplementary services available, the most popular being ANI and DNIS. ANI (automatic number identification) is the ability of the network to identify the calling number. With ANI, the user knows who is calling before answering. DNIS (dialed number information service) is the ability of the network to identify the number that was dialed to reach a user. These two features are important in call center operations.

Customer premise model

As the telephone became a must-have business and management tool, the logistics and costs associated with adding a new telephone line for every new employee or every new phone became overwhelming. Customer premise equipment (CPE) was developed to overcome these problems; it falls into two categories:

§  Access points to network services

§  Extensions of the network itself

The following two examples illustrate the differences:

Key systems (access products)

For small businesses requiring several telephone lines, the key system provides the user with direct access to the network line corresponding to that key. Other users are provided with a small light or "busy lamp" to indicate when a line is busy.

Private branch exchange (PBX)

In large businesses, smaller versions of central office switches, called private branches or PBX systems, enable hundreds or thousands of employees to handle the volume of internal calls. As well, they can share access lines to the network and provide operator services.

For very large corporations with multiple buildings or sites, complete private networks may be installed to carry internal traffic as well as to interconnect to the public network at strategic points to get the best geographic coverage for the lowest cost.