H04Q 1/442
With out-of-voice band signalling frequencies
Official title: with out-of-voice band signalling frequencies
H04Q1/442 (With out-of-voice band signalling frequencies) appears on 12 US grants and 1 published applications in this corpus.
Search patents in H04Q- Granted patents
- 12
- Published applications
- 1
- Assignees
- 12
- Inventors
- 25
- Latest grant
- 5 Oct 1999
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 | 1 | 0 |
| 1985 | 0 | 0 |
| 1986 | 0 | 0 |
| 1987 | 2 | 0 |
| 1988 | 1 | 0 |
| 1989 | 0 | 0 |
| 1990 | 2 | 0 |
| 1991 | 0 | 0 |
| 1992 | 2 | 0 |
| 1993 | 0 | 0 |
| 1994 | 0 | 0 |
| 1995 | 0 | 0 |
| 1996 | 0 | 0 |
| 1997 | 1 | 0 |
| 1998 | 0 | 0 |
| 1999 | 1 | 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.
Subgroups
Granted patents
Recent patents
- Sensing circuit5 Oct 1999US 5,963,885 AAlcatel
- Ring discriminator11 Mar 1997US 5,610,978 AMitel Corporation
- 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
- Interlock circuit for preventing corruption of telephone line signals3 Jul 1990US 4,939,765 AHarris Corporation
Most cited
By later US patents
- Ring discriminator23US 5,610,978 AMitel Corporation · 1997
- Apparatus for selectively enabling subscriber device to respond to ringing signal in dependence upon ringing cadence21US 5,142,569 AData Accessory Corporation · 1992
- Supervisory audio tone detection in a radio channel15US 4,698,769 AAmerican Telephone and Telegraph Company · 1987
- Telephone privacy apparatus11US 4,459,435 A1984
- Telephone system with several terminals on a single line11US 5,119,418 ADolphin Integration · 1992