Hashimoto [45] Jan. 20, 1981 [54] METHOD AND DEVICE FQR CONFIRMING 3,508,205 4/ I970 Kubie ................................. .. 364/200 CORRECT CONNECTION BETWEEN DATA 1;-2321283 ga\\t1_':0n cl al. 3 TERMINALS IN DATA COMMUNICATION ' ' ra 0" """" " 3,680,045 7/1972 Meidan 340/146.1 BA SYSTEM USING TELEPHONE NETWORK 3,780,907 12/ 1973 Oolburn ct al. 179/2 A [75] Inventor: Takemi Hashimoto, Kawasaki, Japan 313051234 4/1974 M88168 ------------ -- 340/146-1 C _ _ 3,806,631 4/1974 Patience et al. 178/4.1 B [73] Assignee: RICOII Company, 11111., Tokyo, Japan 3,392,943 1/1975 Cons-1ab|e __ 341)/149 R _ 3,984,637 10/1976 Caudill 179/2 DP 121] APPL N°" 790550 3,986,169 I0/1976 Kobayashi et 11|. 340/146.1 c [22] Filed: Apr. 25, 1977 4,017,829 4/1977 Sternat ............. .. 340/146.1 c 4,114,139 9/1978 Boyd 61 al. ..................... .. 179/2 DI’ Related U.S. Application Data OTHER PUBLICATIONS [63] Continuation-in-part ofSer. No. 521,135, Nov. 5, 1974, E‘ W‘ Anderson, “Dam Transmission Facilities for aband°“cd' Industrial Customers", Reprinted from Telephony, [30] Foreign Application Priority Data Data Communications, 9/ 21/67, p. 4. Nov. 7, 1973 [JP] Japan 48-125114 P”-many Exam‘-ner___Bernm_d Konick [51] Int. CIR ....................... .. H04M 1/56; H048 3/50 Assistant Examiner—~RandalI P. Myers [52] u.s. Cl. ............................... .. 179/2 DP; 364/200; Attprney. Agent. or Firm—~O00per. Dunham. Clark. 371/24; 371/30; 371/67 Griffin & Moran [58] Field of Search .............. .. 179/2 DP, 1.5 A, 2 A, 119/2 CA, 15 AL, 1.5 R; 17s/22; 340/146.1 c, 1571 . ABSTRACT 146-1 BA, 152 T1 1531 149 R; 364/20011115 F1161 In a system of transceivers which can automatically 9091 200 operate either in calling or called modes, the identifica[56] References Cited E1011 ‘o)f tlfie gagllgfi géitd calls: l1'fl11\.‘:iCC1V€l'S arg ransmi e ac an o ween em an compare U5“ PATENT DOCUMENTS in a manner which tends to minimize erroneous connec2,640,872 6/I953 Hartley et al. 340/ 146.1 C tions and to confirm only correct connections prior to 33141951 4/1957 w111°°K ‘=1 51- 179/2 DP starting the actual transmission of data between the 3,327,288 6/1967 Webber ........... .. 179/2 DP transceivers 3,384,873 5/1968 Sharma .... .. 340/146.1 C ' 3,397,287 8/1968 lshii et al. ........ .. 179/2 R 3,484,694 12/1969 Brothman ct al. .............. .. 179/2 DP 4 18 Drawing Figures
