Enhanced H.245 to 2833 DTMF Interworking

Enhanced H.245 to 2833 and SIP INFO to 2833 DTMF interworking addresses issues experienced where the way the Oracle® Enterprise Session Border Controller timestamps audio RTP packets result in dropped digits and digits with a stutter pattern. These occurrences can cause other network devices to deem the packets unrecoverable (due to jitter), meaning that they will never render the digit.

The Oracle® Enterprise Session Border Controller offers the following:

• Timestamp is based on the current time—The Oracle® Enterprise Session Border Controller can compute the timestamp of the egress 2833 packets using the actual time elapsed in milliseconds since the last RTP packet (rather than incrementing the time by 1 sample). Not only does the Oracle® Enterprise Session Border Controller fill out the timestamp field more accurately, but it also recalculates the checksum.
• End-event 2833 messages default behavior—The Oracle® Enterprise Session Border Controller’s new default behavior is to send three end-event 2833 packets only if the DTMF event is received for:
  • An alphanumeric UII or SIP INFO with no duration
  • A signaled UII or SIP INFO with a duration less than the minimum signal duration (the value you configure using the new media manager configuration min-signal-duration option)

  For a signaled UII or SIP INFO with a duration greater than the minimum signal duration, the Oracle® Enterprise Session Border Controller behaves as it does in prior releases: It sends the initial event packets, any interim packets (if they exist), and the three end packets.

• Configurable duration for the 2833 event—Without the enhancements being configured, the Oracle® Enterprise Session Border Controller uses a 250 millisecond duration for the 2833 event when it receives an alphanumeric UII or a SIP INFO with no specified duration. The result is that 2833 packets are sent at 50-millisecond intervals until the 250 millisecond time expires; then the three end-event packets are sent.

  Now the Oracle® Enterprise Session Border Controller allows you to set the duration of these 2833 events using a new default-2833-duration parameter (with a 100 millisecond default) in the media manager configuration. In addition, the Oracle® Enterprise Session Border Controller uses this configured value (instead of the duration sent in the signaling message) when it receives an UII or SIP INFO with a duration less than the minimum signal duration. It checks to make sure that the value for the default-2833-duration parameter is greater than the minimum signal duration.

• Configurable minimum signal duration value—Without this configured, the Oracle® Enterprise Session Border Controller accepts and uses the duration it receives in the UII or SIP INFO for the 2833 event. However, you can configure this value using the min-signal-duration option in the media manager configuration. If the duration the Oracle® Enterprise Session Border Controller receives is less than the threshold, it uses the value configured in the default-2833-duration parameter.

  If you do not configure this option, then there is no signaling duration threshold.

  Note:

  Timestamp changes and duration changes only take effect when the 2833 timestamp (rfc-2833-timestamp) is enabled in the media manager configuration.