WAS v8.5 > WebSphere applications > Communications enabled applications > Communications Enabled Applications concepts
CEA call flow
In a Web telephony session, users can make phone calls using the ClicktoCall widget in their Web browsers. The call flow diagram illustrates the CEA call flow.
The system application must first be configured with the IP private branch exchange (PBX) address.
The following configuration applies to this call flow:
- A user clicks the ClickToCall widget, which sends an HTTP REST request.
- The Web container calls the system application.
- An HTTP servlet interprets the REST request.
- The system application sends SIP messages to the IP PBX using the ECMA TR/87 standard protocol.
In addition to TR/87, PBX vendors can choose to expose a web service interface based on a WSDL file provided with CEA. This WSDL file is included in the installation path, app_server_root/systemApps/commsvc.ear/commsvc.rest.war/WEB-INF/wsdl/ControllerService.wsdl. Using this WSDL file enables you to configure CEA to call out to a PBX through a web service instead of relying on TR/87.
Restriction: The IP PBX must support the ECMA TR/87 protocol or the CEA web service interface.
- The IP PBX notifies the user agent client (UAC) to call the user agent server (UAS).
- A call is established between the two users.
UAC and UAS are SIP instances.
Figure 1. CEA call flow