Call progress tone system
US4669110A · kind A · utility
6Cited by
2References
4Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Oct 25, 1985 |
| Grant date | May 26, 1987 |
| Priority date | — |
| Expiry date | Oct 25, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04Q3/625
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A tone source is located at each telephone set of a private branch exchange (PBX) or a key telephone system. The tone source provides call progress tones and warble ring tone, as well as a feedback tone in response to the depression of telephone set keypad buttons by the user. The signaling to the central system unit is transmitted via a digital link.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.