H04M 9/006
Exchange line circuits
Official title: {Exchange line circuits (subscriber line circuits H04M3/005)}
H04M9/006 (Exchange line circuits) appears on 33 US grants and 0 published applications in this corpus.
Search patents in H04M- Granted patents
- 33
- Published applications
- 0
- Assignees
- 17
- Inventors
- 50
- Latest grant
- 2 Dec 1997
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 5 | 0 |
| 1977 | 7 | 0 |
| 1978 | 4 | 0 |
| 1979 | 3 | 0 |
| 1980 | 2 | 0 |
| 1981 | 0 | 0 |
| 1982 | 2 | 0 |
| 1983 | 2 | 0 |
| 1984 | 2 | 0 |
| 1985 | 0 | 0 |
| 1986 | 1 | 0 |
| 1987 | 0 | 0 |
| 1988 | 0 | 0 |
| 1989 | 1 | 0 |
| 1990 | 1 | 0 |
| 1991 | 1 | 0 |
| 1992 | 1 | 0 |
| 1993 | 0 | 0 |
| 1994 | 0 | 0 |
| 1995 | 0 | 0 |
| 1996 | 0 | 0 |
| 1997 | 1 | 0 |
By publication year. Applications have been published since 2001.
Recent patents
- Circuit and method for reducing common mode interference in telephone instruments2 Dec 1997US 5,694,460 ALucent Technologies Inc.
- Key telephone interface17 Mar 1992US 5,097,501 AAT&T Bell Laboratories
- Control and interface apparatus for telephone systems10 Sep 1991US 5,048,080 AAT&T Bell Laboratories
- Key telephone system19 Jun 1990US 4,935,957 ANippon Telegraph and Telephone Corporation
- Office line interface circuits8 Aug 1989US 4,856,058 AKabushiki Kaisha Toshiba
No published applications in this class yet.
Most cited
By later US patents
- Method and apparatus for automatically annunciating the completion of a telephone call hold interval18US 3,961,142 A1976
- Control and interface apparatus for telephone systems18US 5,048,080 AAT&T Bell Laboratories · 1991
- Telephone lines status sensor16US 4,446,338 ANorthern Telecom Limited · 1984
- Music on hold for key systems14US 4,588,865 AVodavi Technology Corporation · 1986
- Line circuit for use with a key telephone system13US 4,004,106 AAkzona Incorporated · 1977