Multiple RTP Media Streams per Call Session

The device's SBC application supports multiple RTP media streams per SBC call session. It supports the negotiation of up to five media streams ('m=' line) in the SDP offer/answer model per session. The media can include a combination of any of the following types:

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Audio, indicated in the SDP as 'm=audio'

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Video, indicated in the SDP as 'm=video'

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Text, indicated in the SDP as 'm=text'

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Fax, indicated in the SDP as 'm=image'

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Binary Floor Control Protocol (BFCP), indicated in the SDP as 'm=application <port> UDP/BFCP'

Therefore, the device supports transcoding of various attributes in the SDP offer-answer (e.g., codec, port, and packetization time) per media type. If the device is unable to perform transcoding (e.g., doesn't support the coder), it relays the SBC dialog transparently.

The device transparently forwards Binary Floor Control Protocol (BFCP) signaling over UDP between IP entities (RFC 4582). BFCP is a signaling protocol used by some third-party conferencing servers to share content (such as video conferencing, presentations or documents) between conference participants (SIP clients supporting BFCP). The SDP offer/answer exchange model is used to establish (negotiate) BFCP streams between clients. The BFCP stream is identified in the SDP as 'm=application <port> UDP/BFCP' and a dedicated UDP port is used for the BFCP streams.