System and method for determining clock skew in a packet-based telephony session
US7639716B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Jun 18, 2004 |
| Grant date | Dec 29, 2009 |
| Priority date | — |
| Expiry date | Jun 27, 2025 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L69/24
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A method for determining clock skew in a packet-based telephony session is disclosed. A telephony device receives RTCP SR packets from a remote telephony device transmitting RTP packets in a telephony session. Each control packet includes an NTP time-stamp and a RTP time-stamp. The device determines from two or more of the received SR packets a first relative rate of a remote media card clock to the remote system clock rate. Further, the device determines from two or more transmitted RTCP SR packets, a second relative rate of a local media card clock to the local system clock rate. The device can then be adjusted to take into account the first and second relative rates for optimum buffer management and to more accurately adjust the quality of a session based on one-way packet delay.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.