28 December 2010

IVR Basics: Part 2

DTMF (dual tone multi frequency) is the signal to the phone company that you generate when you press an ordinary telephone's touch keys. In the United States and perhaps elsewhere, it's known as "Touchtone" phone (formerly a registered trademark of AT&T). DTMF has generally replaced loop disconnect ("pulse") dialling. With DTMF, each key you press on your phone generates two tones of specific frequencies. So that a voice can't imitate the tones, one tone is generated from a high-frequency group of tones and the other from a low frequency group.

DNIS (Dialed Number Identification Service) is a telephone service that identifies for the receiver of a call the number that the caller dialed. DNIS works by passing the touch tone digits or DTMF (dual tone multi frequency) to the processing unit where a special facility can read and display them or make them available to the call processing application. DNIS tells the controlling program on this system which number was dialed.
IVR Software utilizes DNIS in several ways. First, IVR programs are initially invoked based upon the call's DNIS. Thus, a specific IVR program can be assigned to each identified phone number routed to a phone system. Once the IVR program has been invoked, it in turn can query the phone system to determine the number dialed. This is important when multiple phone numbers route to the same IVR program.
SS7 protocol:
Signaling System No. 7 (SS7) is a set of telephony signaling protocols which are used to set up most of the world's public switched telephone network telephone calls. The main purpose is to set up and tear down telephone calls. Other uses include number translation, prepaid billing mechanisms, short message service (SMS), and a variety of other mass market services.
SS7 signaling is termed Common Channel Signaling (CCS) in that the path and facility used by the signaling is separate and distinct from the telecommunications channels that will ultimately carry the telephone conversation. With CCS, it becomes possible to exchange signaling without first seizing a facility, leading to significant savings and performance increases in both signaling and facility usage.

TMS (Telephony Media Server): The Nortel Telephony Media Server (TMS) is the core functional module of the MPS 1000. The basic TMS assembly contains local data processors, shared memory, digital signal processors (DSP) for basic resources, data network interfaces (Ethernet), and Computer Telephony (CT) bus interfaces for voice communications. The TMS is installed with at least one phone line interface, a Digital Communications Controller (DCC), in one of the four slots.
A single TMS can support up to eight digital T1 (24 channels/span for a total of 192 lines) or E1 (30 channels/span for a total of 240 lines) spans by using an individual DCC to connect to the Public Switched Telephone Network (PSTN).

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