PRI and BRI1

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Introduction
Integrated Services Digital Network (ISDN) is a set of ITU-T (Telecommunication Standardization Sector of the International Telecommunications Union) standards for digital transmission over ordinary telephone copper wire as well as over other media. ISDN provides the integration of both analog or voice data together with digital data over the same network. ISDN has two levels of service:
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Basic Rate Interface (BRI) Primary Rate Interface (PRI)

ISDN was the Telco’s response to a change in technology that saw modems being installed on analog telephone lines to transfer data over long distances. The toll network was only designed for a limited voice bandwidth and tops out at about 56 Kbps when used as data bandwidth. In addition, analog modems use the same frequencies as telephone audio. You can use the line for data or voice, but only not both at the same time. BRI, the full name is Basic Rate Interface is a 128 Kbit/s service delivered over a pair of standard telephone copper wires. The 144 Kbit/s payload rate is broken down into two 64 Kbit/s bearer channels ('B' channels) and one 16 Kbit/s signaling channel ('D' channel or delta channel). This is sometimes referred to as 2B+D. BRI-ISDN is very popular in Europe but is much less common in North America. It is also common in Japan - where it is known as INS64. PRI, the full name is Primary Rate Interface. It consists of 23 B-channels and one 64 Kbps Dchannel using a T-1 line or 30 B-channels and 1 D-channel using an E1 line. Thus, a Primary Rate Interface user on a T-1 line can have up to 1.544 Mbps service or up to 2.048 Mbps service on an E1 line. PRI uses the Q.931 protocol over the D-channel. The Primary Rate Interface channels are carried on a T-carrier system line (in the U.S., Canada, and Japan) or an E-carrier line (in other countries) and are typically used by medium to large enterprises. The 23 (or 30) B-channels can be used flexibly and reassigned when necessary to meet special needs such as videoconferences. The Primary Rate user is hooked up directly to the telephone company central office.

PRI (Primary Rate Interface)

A PRI (Primary Rate Interface) is a telecommunication standard used in the Integrated Services Digital Network or ISDN, for carrying multiple DS0 voice and data transmissions between two physical locations. PRI was developed specifically for industrial or large quantity users. PRI is an industrial ISDN line whiles the Basic Rate Interface, or BRI, is used to cater to home and small enterprises. ISDN, the Integrated Services Digital Network, is a digital telephone standard that made voice and data services widely available long before the more recent deployment of Enterprise VoIP and MPLS networks. ISDN's Primary Rate Interface is more in demand today than ever. That's because it is tightly integrated with the installed base of telephone trunk lines that are almost universally available. The access structure for the Primary Rate Interface (PRI) is a digital carrier system using time division multiplexing (TDM). In North America and Japan, this consists of 24 channels, usually divided into 23 B channels and 1 D channel, and runs over the same physical interface as T1. PRI has 31 user channels, usually divided into 30 B channels and 1 D channel and is based on the E1 interface. Primary Rate Interfaces (PRI) is deployed for applications requiring either numerous B-channels, or higher bandwidth than just the two B-channels of a Basic Rate Interface (BRI). These applications, in addition to mainframe access, Internet access, and video conferencing are supported on CPE that can terminate these higher speed interfaces. PRI is a type of ISDN connection, that is typically used for connections between a PBX (private branch exchange a.k.a. a telephone exchange operated by customer of telephone company) which is a telephone exchange operated by the customer of a telephone company, and a Central Office of the telephone company or an Inter Exchange Carrier and a CO (central office) or IXC (inter exchange carrier a.k.a. long distance telephone company). PRI uses the public telephone network to carry digital signal for all your voice and data communications needs.

PRI connections can characterized as two ways that is 23 channels supporting voice, data, and video services that can be easily combined or allocated for your own desire. Another way is a 24th channel to support signaling between your equipment and the network. Through the PRI (Primary Rate Interface) service, you will be able to:


Combine voice and data communications and have the ability to upgrade the capacity when desired. Re-allocate capacity at any time. Expect 1.54Mbps capacity. Carry signaling information over a separate channel and speed up the process of your calls Any channel can carry any type of connection, eliminating single-purpose trunks such as Direct Inward Dial, Direct Outward Dial and dedicated video or data lines Allocate more channels to an application in multiples of 64 Kbps If data is your main communication need, the inward data option supports analog, digital data calls, and a digital data only option

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PRI also can be use to support modem banks. A dozen or more dial-up modems can be deployed by an Internet Service Provider at a single location and will communicate with the ISP via the T1 PRI connection. Each modem is supported by a single bearer channel. There are many types of benefits such as:


Digital service integrating voice, data, video and packet switch data on a single access loop Multi-channel, digital pipes supporting different services on separate channels Local exchange access service providing up to T-1 bandwidth (1.5 Mbps or 23B and 1D channels)

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Replacing standard single-purpose trunks with PRI service can save much money. Increase the speed and flexibility of LAN access without dedicated lines. Bandwidth on an as needed basis.

Primary Rate Interface (PRI) service uses the public telephone network to carry a digital signal that can satisfy your company's voice needs in the most efficient, flexible way possible. Carrying the signal information over a separate channel will speed up the origination, termination and any other changes required to process your calls. There have many features of PRI service is service of call-by call, calling line blocking line Id, DID & DOD & Data and Toll-Free Support. Apart From that, non-facilities associated signaling, 64 Kbps clear channel and back-up D channel also are the features of PRI. The advantage of primary rate interface or PRI is that the 23 or 30 B channels can be used in various combinations for specific data transmission needs, such as a videoconferencing, allowing bulk data transfer to be achieved more flexibly.

BRI (Basic Rate Interface)
The Basic Rate Interface (BRI) is the minimal service obtainable for ISDN (Integrated Services Digital Network). ISDN is a digital phone service that is meant to replace the traditional analog phone system. By using BRI, the MERLIN MAGIX Integrated System can connect its users to the speed and accuracy of ISDN services. Basic Rate Interface (BRI) is a level of data transfer available to users who have an Integrated Services Digital Network (ISDN) connection, and it is mainly used for Internet connectivity. This type of connection is mostly used by home users, small-business owners, and others who need less bandwidth. The Basic Rate Interface is the lower level of service offered, as compared to the Primary Rate Interface (PRI), which has more channels and higher bandwidth. PRI is used primarily by those with larger bandwidth needs, such as a bigger business or a school. BRI consists of two 64-Kbit/sec B channels and one 16-Kbit/sec D channel. Each B channel can carry a single digitized voice call or can be used as a data channel. The B channels can also be combined to form a single 128-Kbit/sec data channel. The D channel is used for call establishment and other signaling.

Basic Rate Interface can be delivered with physical interfaces. It mostly depends on the specific use of the network as well geographical factors, such as distance, as to which interface will be implemented. The most common format is known as an S/T interface, and it is the easiest to set up and use in home-subscriber networks. The following benefits are provided by NI-1 BRI service:


Speed. Data calls to outside destinations can be established on the same B-channels used for voice calls if the service allows; modems and dedicated, conditioned lines/trunks are not needed. By supporting high-speed digital data transmission, BRI provides the capability for videoconferencing and Group IV (G4) fax by using existing wiring. Each B-channel supports up to 64 kbps throughput.



Improved Toll Restriction. The ways that Toll Restriction can be bypassed are limited on BRI lines/trunks. Specifically, BRI service eliminates three types of toll fraud:
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Because dialing is in the form of out-of-band messages that must be generated by the system, a person cannot use a Touch-Tone generating device, such as a pocket dialer, to send dialed digits directly through the system to the line/trunk.

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Without BRI service, Toll Restriction can be deceived by dialing digits on a loopstart line before the far-end switch applies dial tone. These initial digits may indicate a local call to the system's toll-restriction checking while the subsequent digits, those actually recognized by the far-end switch, may produce a toll call. This is not possible with BRI service, because the system's toll-restriction check screens every dialed digit.

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A BRI line's far-end disconnect signal provides a reliable indication when a call ends, and a new call cannot be initiated until the line has been released from the prior call on both ends. This prevents a person, waiting off-hook for the restoration of dial tone after a previous call, from placing a second call before Toll Restriction is reapplied.



Reliable Indication of Far-End Disconnect. This prevents an incoming call from being blocked because a line/trunk has not been released when a call is ended.

Conclusion
After doing this assignment, I and my group members can learn that what the ISDN is. Integrated Services Digital Network (ISDN) is a set of ITU-T (Telecommunication Standardization Sector of the International Telecommunications Union) standards for digital transmission over ordinary telephone copper wire as well as over other media. After that, we also study that ISDN have two levels of service that is PRI and BRI. PRI stand for Primary Rate Interface is a digital carrier system using time division multiplexing (TDM). While BRI stand for Basic Rate Interface is the minimal service obtainable for ISDN (Integrated Services Digital Network). Each level service has its features and application. PRI consists of 24 channels, usually divided into 23 B channels and 1 D channel, and runs over the same physical interface as T1, while BRI consists of two 64-Kbit/sec B channels and one 16-Kbit/sec D channel. Each B channel can carry a single digitized voice call or can be used as a data channel. Lastly, I and my group member also know that the features of PRI, that is service of call-by call, calling line blocking line Id, DID & DOD & Data and Toll-Free Support. Apart From that, nonfacilities associated signaling, 64 Kbps clear channel and back-up D channel also are the features of PRI.

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