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Computer telephony integration, also called computer–telephone integration or CTI, is a common name for any technology that allows interactions on a telephone and a computer to be integrated or coordinated. The term is predominantly used to describe desktop-based interaction for helping users be more efficient, though it can also refer to server-based functionality such as automatic call routing.
2.9
Computer Telephony (CT)
Computer telephony integration,
also called computer–telephone integration or CTI, is a common
name for any technology that allows interactions on a telephone and a computer to
be integrated or coordinated. The term is predominantly used to describe
desktop-based interaction for helping users be more efficient, though
it can also refer to server-based functionality such as automatic call
routing.
COMMON FUNCTIONS
CTI applications tend to run on either a user's desktop, or an unattended server.
Common desktop functions provided by CTI applications
Common server functions provided by CTI applications
Computer-phone connections can be split into two categories:
First-party call control
Operates as if there is a direct connection between the user's computer and the phone set. Examples are a modem or a phone plugged directly into the computer. Typically, only the computer associated with the phone can control it by sending commands directly to the phone and thus this type of connection is suitable for desktop applications only. The computer can generally control all the functions of the phone at the computer user's discretion.
Third-party call control
Interactions between arbitrary numbers of computers and telephones are made through and coordinated by a dedicated telephony server. Consequently, the server governs which information and functions are available to a user. The user's computer generally connects to the telephony server over the local network.
HISTORY AND MAIN CTI TECHNOLOGIES
The origins of CTI can be found in simple screen population (or "screen pop") technology. This allows data collected from the telephone systems to be used as input data to query databases with customer information and populate that data instantaneously in the customer service representative screen. The net effect is the agent already has the required screen on his/her terminal before speaking with the customer.
This technology started gaining widespread adoption in markets like North America and West European countries.
There were several standards which had a major impact in the ´normalization´ of in the industry, previously fully closed and proprietary to each PBX/ACD vendor. On the software level, the most adopted interface by vendors is the CSTA standard, which is approved by the standards body ITU. Other well known CTI standards in the industry are JTAPI, TSAPI and TAPI: JTAPI, the Java Telephony API is promoted by Sun; TSAPI, originally promoted by the AT&T (later Lucent then Avaya) and Novell, by far the most adopted in large scale contact centers; Microsoft pushed their own initiative also, and thus TAPI was born, with support mostly from Windows applications.
Among the key players in this area, Lucent played a big role and IBM acquired ROLM Inc, a US pioneer in ACDs, in an attempt to normalize all major PBX vendor interfaces with its CallPath middleware. This attempt failed when it sold this company to Siemens AG and gradually divested in the area. A pioneer startup that combined the technologies of voice digitization, Token Ring networking, and time-division multiplexing was ZTEL of Wilmington, Massachusetts. ZTEL's computer-based voice and data network combined user-programmable voice call processing features, protocol conversion for automated "data call processing," database-driven directory and telset definitions, and custom LSI chipset technology. Unfortunately, ZTEL ran into funding and management problems, and it ceased operation in 1986.
Two other important players were Digital Equipment Corporation and Tiger Software (now Mondago). Digital Equipment Corporation developed CT Connect which includes vendor abstraction middleware. CT Connect was then sold to Dialogic, which in turn was purchased by Intel. This CTI software, known as CT Connect, was most recently sold in 2005 to Envox Worldwide. Tiger Software produced the SmartPhone suite which was primarily aimed at allowing CRM application vendors to add CTI functionality to their existing applications with minimal effort. After changing their name to Mondago, Tiger Software went on to produce the Go Connect server application, which is aimed at providing at helping other CTI vendors integrate with a wider range of telephone systems.
Many of the early CTI vendors and developers have changed hands over the years. An example is Nabnasset, an Acton, Massachusetts firm that developed a CORBA based CTI solution for a client and then decided to make it into a general product. It merged with Quintus, a customer relationship management company, which went bankrupt and was purchased by Avaya Telecommunications. Smaller organisations have also survived from the early days and have leveraged their heritage to thrive. However, many of the 1980s startups that were inspired by the "Bell Breakup" and the coming competitive telephony marketplace, did not survive the decade.
On the hardware level,
there was a paradigm shift since 1993, with emerging standards from IETF,
which led to several new players like Dialogic, Brooktrout (now part
of Dialogic), NMS (also now part of Dialogic) and Aculab offering telephony
interfacing boards for various networks and elements.
2.10
Cables for telephony
Twisted pair
Twisted pair cabling is a type of wiring in which two conductors (the forward and return conductors of a single circuit) are twisted together for the purposes of canceling out electromagnetic interference (EMI) from external sources; for instance, electromagnetic radiation from unshielded twisted pair (UTP) cables, and crosstalk between neighboring pairs. It was invented by Alexander Graham Bell.
Explanation
In balanced pair operation, the two wires carry equal and opposite signals and the destination detects the difference between the two. This is known as differential modetransmission. Noise sources introduce signals into the wires by coupling of electric or magnetic fields and tend to couple to both wires equally. The noise thus produces a common-mode signal which is cancelled at the receiver when the difference signal is taken. This method starts to fail when the noise source is close to the signal wires; the closer wire will couple with the noise more strongly and the common-mode rejection of the receiver will fail to eliminate it. This problem is especially apparent in telecommunication cables where pairs in the same cable lie next to each other for many miles. One pair can induce crosstalk in another and it is additive along the length of the cable. Twisting the pairs counters this effect as on each half twist the wire nearest to the noise-source is exchanged. Providing the interfering source remains uniform, or nearly so, over the distance of a single twist, the induced noise will remain common-mode. Differential signaling also reduces electromagnetic radiation from the cable, along with the associatedattenuation allowing for greater distance between exchanges.
The twist rate (also called pitch of the twist, usually defined in twists per meter) makes up part of the specification for a given type of cable. Where nearby pairs have equal twist rates, the same conductors of the different pairs may repeatedly lie next to each other, partially undoing the benefits of differential mode. For this reason it is commonly specified that, at least for cables containing small numbers of pairs, the twist rates must differ.[1]
In contrast to FTP (foiled twisted pair) and STP (shielded
twisted pair) cabling, UTP (unshielded twisted pair) cable is not
surrounded by any shielding. It is the primary wire type for telephone usage and is very common for computer networking, especially as patch cables or temporary network connections due
to the high flexibility of the cables.
History
The earliest telephones used telegraph lines, or open-wire single-wire earth return circuits. In the 1880s electric trams were installed in many cities, which induced noise into these circuits. Lawsuits being unavailing, the telephone companies converted to balanced circuits, which had the incidental benefit of reducing attenuation, hence increasing range.
As electrical power distribution became more commonplace, this measure proved inadequate. Two wires, strung on either side of cross bars on utility poles, shared the route with electrical power lines. Within a few years the growing use of electricity again brought an increase of interference, so engineers devised a method called wire transposition, to cancel out the interference. In wire transposition, the wires exchange position once every several poles. In this way, the two wires would receive similar EMI from power lines. This represented an early implementation of twisting, with a twist rate of about four twists per kilometre, or six per mile. Such open-wire balanced lines with periodic transpositions still survives today in some rural areas.
Twisted pair cables were invented by Alexander Graham Bell in 1881.[2] By 1900, the entire American telephone line network was either twisted pair or open wire with transposition to guard against interference. Today, most of the millions of kilometres of twisted pairs in the world are outdoor landlines, owned by telephone companies, used for voice service, and only handled or even seen by telephone workers.
Unshielded Twisted Pair (UTP)
UTP cables are found in many Ethernet networks and telephone systems. For indoor telephone applications, UTP is often grouped into sets of 25 pairs according to a standard 25-pair color code originally developed by AT&T. A typical subset of these colors (white/blue, blue/white, white/orange, orange/white) shows up in most UTP cables.
For urban outdoor telephone cables containing hundreds or thousands of pairs, the cable is divided into smaller but identical bundles. Each bundle consists of twisted pairs that have different twist rates. The bundles are in turn twisted together to make up the cable. Pairs having the same twist rate within the cable can still experience some degree of crosstalk. Wire pairs are selected carefully to minimize crosstalk within a large cable.
UTP cable is also the most common cable used in computer networking. Modern Ethernet, the most common data networking standard, utilizes UTP cables. Twisted pair cabling is often used in data networks for short and medium length connections because of its relatively lower costs compared to optical fiber and coaxial cable.
UTP is also finding increasing
use in video applications, primarily in security cameras. Many middle to high-end camera
Cable shielding
Twisted pair cables are often shielded in an attempt to prevent electromagnetic interference. Because the shielding is made of metal, it may also serve as a ground. However, usually a shielded or a screened twisted pair cable has a special grounding wire added called a drain wire. This shielding can be applied to individual pairs, or to the collection of pairs. When shielding is applied to the collection of pairs, this is referred to as screening. The shielding must be grounded for the shielding to work, and is improved by grounding the drain wire along with the shield.
Shielded twisted pair (STP or STP-A)
150 ohm STP shielded twisted pair cable defined by the IBM Cabling System specifications and used with token ring or FDDI networks. This type of shielding protects cable from external EMI from entering or exiting the cable and also protects neighboring pairs from crosstalk.
Screened twisted pair (ScTP or F/TP)
ScTP cabling offers an overall sheath shield across all of the pairs within the 100 Ohm[3] twisted pair cable. F/TP uses foil shielding instead of a braided screen. This type of shielding protects EMI from entering or exiting the cable.
Screened shielded twisted pair (S/STP or S/FTP)
S/STP (Screened Shielded Twisted Pair) or S/FTP (Screened Foiled Twisted Pair) cabling offer shielding between the pair sets and an overall sheath shield within the 100 Ohm twisted pair cable. This type of shielding protects EMI from entering or exiting the cable and also protects neighboring pairs from crosstalk.
S/STP cable [4] is both individually shielded (like STP cabling) and also has an outer metal shielding covering the entire group of shielded copper pairs (like S/UTP). This type of cabling offers the best protection from interference from external sources, and also eliminates alien crosstalk.[4]
Note that different vendors and authors use different terminology (i.e. STP has been used to denote both STP-A, S/STP, and S/UTP).[3] See below for the ISO/IEC attempt to internationally standardise the various designations.
Comparison of some old and
new abbreviations, according to ISO/IEC 11801:
| Old name | New name | cable screening | pair shielding |
| UTP | U/UTP | none | none |
| STP | U/FTP | none | foil |
| FTP | F/UTP | foil | none |
| S-STP | S/FTP | braiding | foil |
| S-FTP | SF/UTP | foil, braiding | none |
The code before the slash designates the shielding for the cable itself, while the code after the slash determines the shielding for the individual pairs: