Data Communications Networking Devices - 4th Ed.pdf

68 _______________________________ FUNDAMENTAL WIDE AREA NETWORKING CONCEPTSCross-licensed technologyAs the deregulation of the US telephone industry progressed,hundreds of vendorsdeveloped products for the resulting market. Many vendors cross-licensed technology,suchas the command set which de®nes the operation of intelligentmodems. Due to this,another area of de facto standards developed based uponconsumer acceptance of commercial products. In certain cases, de facto standardshave evolved into de jure standards with their adoption by one or more standardmakingorganizations.BellcoreA third area of de facto standards is Bellcore. Upon divestiture in 1984,AT&Tformed Bell Communications Research,Inc. Bellcore) with its seven regional Bellholding companies. Bellcore provides technical and research support to theseholding companies in much the same way that Bell Laboratories supported AT&T.Bellcore maintains common standards for the nation's telephone systems,ensures asmoothly operating telephone network and coordinates telecommunications operationsduring national emergencies. With approximately 7000 employees,hundredsof research projects and an annual budget of approximately $1 billion,Bellcore isamong the largest research and engineering organizations in the United States.Like AT&T,Bellcore publishes a catalog of technical publications calledCatalog 10000. The Bellcore catalog list approximately 500 publications that varyin scope from compatibility guides,which list the interface speci®cations that mustTable 1.23Communications reference publication sourcesANSIITU General Secretariat1430 Broadway International Telecommunication UnionNew York, NY 10018, USAPlace des Nations212) 354-3300 1211 Geneva 20, SwitzerlandAT&TIEEECustomer Information Center345 East 47th StreetIndianapolis, IN 46219, USANew York, NY 10017, USA800) 432-6600 212) 705-7900317) 352-8557Bell Communications Research US Department of CommerceInformation Operations CenterNational Technical Information Service60 New England Avenue 5285 Port Royal Rd.Piscataway, NJ 08854, USASpring®eld, VA 22161, USA201) 981-5600 703) 487-4650EIAStandard Sales2001 Eye Street NWWashington DC 20006, USA202) 457-4966