H04Q 1/4423
Using one signalling frequency
Official title: {using one signalling frequency}
H04Q1/4423 (Using one signalling frequency) appears on 4 US grants and 1 published applications in this corpus.
Search patents in H04Q- Granted patents
- 4
- Published applications
- 1
- Assignees
- 4
- Inventors
- 10
- Latest grant
- 25 Aug 1992
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1977 | 1 | 0 |
| 1978 | 0 | 0 |
| 1979 | 1 | 0 |
| 1980 | 0 | 0 |
| 1981 | 0 | 0 |
| 1982 | 0 | 0 |
| 1983 | 0 | 0 |
| 1984 | 0 | 0 |
| 1985 | 0 | 0 |
| 1986 | 0 | 0 |
| 1987 | 0 | 0 |
| 1988 | 0 | 0 |
| 1989 | 0 | 0 |
| 1990 | 0 | 0 |
| 1991 | 0 | 0 |
| 1992 | 2 | 0 |
| 1993 | 0 | 0 |
| 1994 | 0 | 0 |
| 1995 | 0 | 0 |
| 1996 | 0 | 0 |
| 1997 | 0 | 0 |
| 1998 | 0 | 0 |
| 1999 | 0 | 0 |
| 2000 | 0 | 0 |
| 2001 | 0 | 0 |
| 2002 | 0 | 0 |
| 2003 | 0 | 0 |
| 2004 | 0 | 0 |
| 2005 | 0 | 0 |
| 2006 | 0 | 1 |
By publication year. Applications have been published since 2001.
Recent patents
- Apparatus for selectively enabling subscriber device to respond to ringing signal in dependence upon ringing cadence25 Aug 1992US 5,142,569 AData Accessory Corporation
- Telephone system with several terminals on a single line2 Jun 1992US 5,119,418 ADolphin Integration
- AC supervisory signal detector circuit9 Jan 1979US 4,133,982 AGTE Automatic Electric Laboratories Incorporated
- Out-of-band signaling method and apparatus to adapt payphones to telephone systems1 Mar 1977US 4,010,328 AThe Anaconda Company
Most cited
By later US patents
- Apparatus for selectively enabling subscriber device to respond to ringing signal in dependence upon ringing cadence21US 5,142,569 AData Accessory Corporation · 1992
- Telephone system with several terminals on a single line11US 5,119,418 ADolphin Integration · 1992
- AC supervisory signal detector circuit6US 4,133,982 AGTE Automatic Electric Laboratories Incorporated · 1979
- Out-of-band signaling method and apparatus to adapt payphones to telephone systems5US 4,010,328 AThe Anaconda Company · 1977