Patent search ap:("BELL TELEPHONE LABOR INC") AND inv:"PFROMMER JOHN S" Page 1

1.

发明授权
Integrated two-and four-wire telephone switching system 失效
Title translation: 集成二线和四线电话交换系统

公开(公告)号：US3150236A

公开(公告)日：1964-09-22

申请号：US13463361

申请日：1961-08-29

Applicant: BELL TELEPHONE LABOR INC

Inventor： GORGAS JOHN W , HURST GEORGE A , PFROMMER JOHN S , SCHEER WILLIAM H

IPC: H04Q3/00

CPC classification number: H04Q3/0004

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