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US005465388A
United States Patent [19] [ii] Patent Number: 5,465,388
Zicker [45] Date of Patent: Nov. 7,1995
4,916,728 4/1990 Blair 379/59
5,020,091 5/1991 Krolopp et al 379/58
5,159,625 10/1992 Zicker 379/59
5,228,074 7/1993 Mizikovsky 379/59
5,301,359 4/1994 Van den Heuvel et al 455/54.1
FOREIGN PATENT DOCUMENTS
0179938 8/1991 Japan 455/58.1
Primary Examiner—Reinhard J. Eisenzopf
Assistant Examiner—Thanh Le
Attorney, Agent, or Firm—Lowell W. Gresham; Jordan M.
Meschkow
[57] ABSTRACT
An emergency portable cellular radiotelephone (10) communicates with the one of A and B cellular systems that offers the best signalling. The radiotelephone may be energized from an internal battery (50) or an external power source (62). A single switch (38) is used to instigate emergency communication services. When a signalling channel is available and the switch (38) is activated, the radiotelephone (10) requests the placement of a call to a "911" phone number. Once the call is established, it may not be terminated at the radiotelephone (10), other than by removing power.
22 Claims, 5 Drawing Sheets
