Transrating

The Oracle® Enterprise Session Border Controller can transrate media as it exits the Oracle® Enterprise Session Border Controller into the network. Transrating is also known as forced packetization time (ptime), and is used to enforce a configured ptime within a realm. Transrating is often desirable when devices in a realm can only accept media with a specific ptime, or to optimize bandwidth.

If this feature is configured, the media portion of a call is transrated regardless of which codecs are ultimately chosen for each realm as long as they are transcodable. This allows realms that have devices that can only use a single packetization interval to interwork with devices that may or may not have the same packetization capabilities.

You must enable force-ptime in the egress codec policy and then specify the packetization time to force. When force ptime is enabled, it implicitly masks all codecs not of the specified packetization time that are listed in that codec policy’s allow codecs and add codecs on egress parameters. For example, if force ptime is enabled with a packetization time of 20 ms, then no G723 codecs (which are only available at 30, 60, and 90 ms) may be active via codec policy in that realm.

Transrating occurs when forced-ptime is enabled and the offered and answered ptimes do not match and the top non-Signaling codec of A1 and top non Signaling codec of O1 are Transcodable.

Note:

Answered ptime A1 does not have to be equal to the ptime inserted into the outgoing offer O2, it just has to be different than the offer the Oracle® Enterprise Session Border Controller received (O1).

Please refer to Transcodable Codecs for current list of ptimes per codec supported by the DSPs.