Signaling and handling method for proxy transcoding of encoded voice packets in packet telephony applications
AssigneeCisco Technology, Inc.
InventorsMichael E. Knappe, David R. Oran
Life of this patent
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Abstract
Voice packets are redirected in packet telephony applications to a codec proxy system that makes voice endpoints involved in an end-to-end call appear to be using the voice codec required of it by the other endpoint, even if the endpoints do not possess the required codec capability. The codec proxy system acts as a broker during initial capability negotiations, and as a real-time transcoding facility between disparate codec capabilities once voice traffic begins. The resulting system allows non-standard, cost-optimized and/or feature specific packet voice endpoints to interoperate in a standards-based network.
Claims11
A system for proxying between different telephony systems trying to establish telephone calls in a packet network, comprising:
- a first telephony system encoding signals generated at a first endpoint into packets transmitted over the packet network and decoding packets received over the packet network into audio signals at the first endpoint;
- a second telephone system encoding signals generated at a second endpoint into packets transmitted over the packet network and decoding the packets received over the packet network into signals at the second endpoint;
- and
- a proxy system analyzing how the packets are encoded and decoded at both the first and second telephony systems and proxying the encoding and decoding of the packets so that telephone calls can be established between disparate first and second telephony systems,
- wherein the proxy system includes a packet transcoding and rebuffering circuit that decodes packets from a sending one of the telephony systems and re-encodes the decoded packets into a format compatible with a receiving one of the telephony systems.
A method for proxying codecs at opposite endpoints in a packet network, comprising:
- determining what codec capabilities a first one of the endpoints in the packet network has for encoding and decoding audio or video signals;
- determining what codec capabilities a second one of the endpoints in the packet network has for encoding and decoding audio or video signals;
- brokering which codecs to use in the first and second endpoints according to the codec capabilities so a telephone call can be established over the packet network between the first and second endpoints, wherein brokering codecs comprises the following:
- spoofing both the first and second endpoint into believing each is encoding and decoding the audio signals using a common codec;
- decoding encoded audio packets sent by a first one of the endpoints into speech samples;
- and
- reencoding the decoded speech back into audio packets compatible with a codec at a second receiving one of the endpoints.
A codec proxy system for conducting telephone calls between different telephony systems in a packet network, comprising:
- a first capability exchange proxy for communicating with a first one of the telephony systems;
- a second capability exchange proxy for communicating with a second one of the telephony systems;
- a capability exchange broker identifying and selecting codecs in the first and second telephony systems and communicating the identified codecs through the first and second capability exchange proxy;
- and
- a packet transcoding and rebuffering circuit coupled to the capability exchange broker that transcodes audio packets from a sending one of the telephony systems to an encoding scheme compatible with a receiving one of the telephony systems when the first and second telephony systems are not compatible.
Dependencies are inferred from the claim text.