Signaling-Only Mode

The SBC supports a signaling-only mode so that the SBC participates in the exchange of signaling messages that set up a call but does not reserve or allocate any media resources for the session. The media component of the session is handled as direct media between the call participants.

Provisioning the SBC as a signaling-only SBC (SO-SBC) is done at the global level by setting a single configuration option. Once the SBC is operating as an SO-SBC, its remaining configuration becomes simplified because the configuration needed to enable direct-media handling is set automatically. By configuring the SBC in signaling-only mode, direct media is automatically enabled on all trunk groups and all IPSPs. The direct media configuration automatically provided enables intra-SBC and inter-SBC scenarios as described in the "IAD-to-IAD Calls" section of the page Direct Media.

Because they are not required by the SO-SBC, the configuration options for media provisioning are no longer visible in the CLI or in the EMA UI once the SBC is placed in signaling-only mode. However if media options were configured prior to entering signaling-only mode they are retained and restored if the SBC is taken out of signaling-only mode.

The SBC Accounting Records identify calls that occur while the SBC is configured as an SO-SBC by including the value SO-g in the SO-SBC field. Refer to CDR Field Descriptions for CDR details.