SIP REFER with Replaces

To support enterprise and call center applications, the Oracle Communications Session Border Controller provides the ability for one party participating in a three-way call to request direct connectivity between the other two parties and to leave the call silently when that connectivity is established. SIP supports this function using the Replaces header in a REFER message, also known as REFER with Replaces.

The most common application of REFER with Replaces handling occurs in a high-level sequence like this:

1. The customer calls a customer service line and reaches—via the Oracle Communications Session Border Controller—an IVR/ACD (Interactive Voice Response system/Automatic Call Distribution system). In some architectures, these are two separate elements.
2. Based on the customer’s selection from the menu of options, the IVR/ACD contacts an agent via the Oracle Communications Session Border Controller.
3. Since the ultimate goal is for the IVR/ACD to drop out of the path, it sends a REFER with Replaces to the Oracle Communications Session Border Controller. This message indicates the Oracle Communications Session Border Controller should replace the IVR/ACD endpoint in the call leg with the agent’s endpoint.
4. The Oracle Communications Session Border Controller processes the REFER with Replaces, issuing ReINVITEs to the customer with the agent’s parameters.
5. The IVR/ACD drops out of the media path once the bridged call between the customer and the agent is established.

   Note that direct media connectivity between endpoints must be possible in order for the REFER with Replaces to be carried out properly. For example, if both endpoints (such as the customer and agent from the example above) are behind the same firewall, direct media connectivity should be possible. However, if one endpoint is behind a firewall and the other is not, then direct media connectivity may not be possible.

   For licensing capacity purposes, note that a bridged session counts as a single call.

SIP REFER with Replaces Configuration

You enable SIP REFER with Replaces handling either in the realm configuration or in the session agent configuration. This section show you how to configure the feature for session agent, though the steps are the same for adding this feature to a realm.

To enable sending ReINVITES to a referred agent on an existing session/dialog:

1. In Superuser mode, type configure terminal and press Enter.

   ORACLE# configure terminal

2. Type session-router and press Enter.

   ORACLE(configure)# session-router
   ORACLE(session-router)#

3. Type session-agent and press Enter.

   ORACLE(session-router)# session-agent
   ORACLE(session-agent)#

   If you are adding support for this feature to a pre-existing configuration, then you must select (using the ACLI select command) the configuration that you want to edit.

4. options—Set the options parameter by typing options, a Space, and then the option name refer-reinvite. Then press Enter.

   ORACLE(session-agent)# options +refer-reinvite

   If you type the option without the plus sign, you will overwrite any previously configured options. In order to append the new options to this configuration’s options list, you must prepend the new option with a plus sign as shown in the previous example.