The Unspecified Flow of Call-Event Messages

The relative order of call-event messages and any corresponding agent-state-change event messages is not specified. An agent-state-event message indicating the agent is in the "talking" state, for example, might be sent before or after the corresponding call established event message.

When an event occurs that would conceptually result in two or more event messages being generated at the same time, the client must be prepared to handle the messages arriving in any order. For example, an agent answering an inbound call might generate both a CALL_ESTABLISHED_EVENT and an AGENT_STATE_EVENT message. These can be received by a client in either order, and other event messages can be sent to the client in between.

Figure 1 shows a typical unsolicited call-event message flow.