. The Bell System technical journal . United States a large develop-ment of two-party and four-party lines. The two-party stations areprovided with selective ringing so that each station is signaled onlyfor its own telephone messages, and the four-party stations are pro-vided in some places with selective ringing and in others with semi-selective ringing. Party lines have furnished a satisfactory means of providing serviceto small users and have been an important factor in the developmentof new fields of service in residences. To care for situations where something more than a single line TELE
. The Bell System technical journal . United States a large develop-ment of two-party and four-party lines. The two-party stations areprovided with selective ringing so that each station is signaled onlyfor its own telephone messages, and the four-party stations are pro-vided in some places with selective ringing and in others with semi-selective ringing. Party lines have furnished a satisfactory means of providing serviceto small users and have been an important factor in the developmentof new fields of service in residences. To care for situations where something more than a single line TELEPHONE SYSTEM OF THE UNITED STATES 11 with one or two telephones is needed, but where an inter-communi-cating system or private branch exchange is not justified, so-calledwiring plans are used which provide various arrangements for associ-ating the station equipment with the telephone lines. For the mostpart the customers needs are satisfactorily met by one of the tenstandard arrangements in general use. A specific example is that of. Fig. 4—-Telephone booth provided for public telephone stations. two central office lines with two main and two extension to or from either telephone line may be made from any one ofthe four telephones. Answering at a main station provides privacyby cutting off all the other telephones. There are in the United States a considerable number of extensionstations. At the present time there are in the Bell System over 12 BELL SYSTEM TECHNICAL JOURNAL million of such stations. This number is rapidly increasing particu-larly for residence use as people appreciate further the advantagesof having telephones in a number of convenient locations. The bestresidences are more and more being equipped to have telephonesavailable in all parts of the house. In order to make telephone service possible for those people whosesense of hearing is more or less deficient, special sets are means of a vacuum tube amplifier which the user can
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
