Telephonic communications – Telephone line or system combined with diverse electrical... – Having transmission of a digital message signal over a...
Patent
1989-04-03
1991-02-19
Ng, Jin F.
Telephonic communications
Telephone line or system combined with diverse electrical...
Having transmission of a digital message signal over a...
379 93, 379215, H04M 320, H04M 1106
Patent
active
049950746
ABSTRACT:
A system is provided in a circuit switched network data transmission link between a user terminal and a host computer in instances where the terminal is connected to the network by a single telephone line and the terminal user has subscribed to a telephone company service feature such as call waiting. The system includes an interface at the terminal location between the telephone line and the terminal equipment. During a data session the interface detects a call waiting signal and generates a user signal. If the user desires to take the incoming call and suspend a data session, the interface responds to the telephone receiver being lifted off-hook and communicates through the circuit switched network with an interface at the host end of the communication. The host interface is programmed to maintain the data session at the host computer during a suspension of the communication by generating a signal simulating a terminal location signal. The terminal interface locally generates a signal indicating that the host is not ready and toggles the telephone company central office to switch the user's line to the incoming call. To resume the data session, the user places the telephone instrument on hook and the terminal interface toggles the central office to access the host interface for the purpose of resuming the data session.
REFERENCES:
patent: 4751726 (1988-06-01), Hepp et al.
patent: 4754326 (1988-06-01), Kram et al.
patent: 4852151 (1989-07-01), Dittakavi et al.
"Microelectronics Data Book", Issue 5, 1/1988, pp. 3-157 to 3-161, (Exhibit A).
AT&T "Functional Product Class Criteria-PBX", AT&T Technical Reference, 9/1978 (Exhibit B).
S. Munich, "Monolithic Modem Chip Eases .mu.P's Phone Access", EDN Magazine, 1984, pp. 2-187 to 2-198, (Exhibit C).
"CMOS Logic Databook", table of contents, 1988 edition.
Goldman Bruce J.
Goldman Gerald M.
Chan Wing F.
Ng Jin F.
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