Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Zwietusch E & Co GmbhfiledCriticalZwietusch E & Co Gmbh
Publication of CH219811ApublicationCriticalpatent/CH219811A/de
H04M17/00—Prepayment of wireline communication systems, wireless communication systems or telephone systems
H04M17/02—Coin-freed or check-freed systems, e.g. mobile- or card-operated phones, public telephones or booths
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04M—TELEPHONIC COMMUNICATION
H04M1/00—Substation equipment, e.g. for use by subscribers
H04M1/66—Substation equipment, e.g. for use by subscribers with means for preventing unauthorised or fraudulent calling
H04M1/677—Preventing the dialling or sending of predetermined telephone numbers or selected types of telephone numbers, e.g. long distance numbers
Landscapes
Engineering & Computer Science
(AREA)
Computer Security & Cryptography
(AREA)
Signal Processing
(AREA)
Computer Networks & Wireless Communication
(AREA)
Monitoring And Testing Of Exchanges
(AREA)
CH219811D1939-11-121940-12-13Zonenbestimmer in Fernsprechanlagen, insbesondere zur Gebührenkontrolle in Münzfernsprechern mit Netzgruppenverkehr.
CH219811A
(de)