IWF H.245 Signaling Support for G.726
In addition to providing G.726 support for pure SIP and pure H.323 calls, the Oracle® Enterprise Session Border Controller supports the G.726 payload type for H.245 and calls that require interworking (IWF) between SIP and H.323.
For IWF calls using ITU-T G.726 as the audio codec, the SIP call leg requires G.726 in the SDP. The H.323 side of the call signals G.726 (in the H.245 openLogicalChannel and TerminalCapabilitySet messages) by including a GenericCapability defining G.726 as the codec. In the GenericCapability, the capabilityIdentifier and maxBitRate parameters identify G.726. While a capabilityIdentifier with 0.0.7.726.1.0 designates G.726, the maxBitRate designate the data transmission rate.
| Codec | Max Bit Rate | Data Rate |
|---|---|---|
| G726-16 | 160 | 16 kbit/s |
| G726-24 | 240 | 24 kbit/s |
| G726-32 | 320 | 32 kbit/s |
| G726-40 | 400 | 40 kbit/s |
To support G.726 for IWF calls, the Oracle® Enterprise Session Border Controller converts the G726-X value in the SDP of SIP messages to a GenericCapability structure in H.323/H.245 messages, and the conversion works the same way in reverse.
