Communication System Architecture

A method for effecting communication events between a user device and one or more additional endpoints connected via a communication network of a communication system, the communication system comprising a media modality controller configured to manage media modality of an established communication event and a call controller configured to establish the communication event, the method comprising the user device:

• receiving instructions via the communication network from the call controller;
• and
• receiving instructions via the communication network from the media modality controller;
• wherein the user device is configured to execute a call agent and a media agent, the call agent being configured to be responsive to the instructions received from the call controller and the media modality agent being configured to be responsive to the instructions received from the media modality controller but not to the instructions received from the call controller.

At least one computer readable medium storing executable code which is configured to implement a method of managing a communication event between endpoints connected via a communication network of a communication system comprising a plurality of processing units, each having access to computer storage holding executable code modules for managing the communication event, the code modules being configured to implement a first media modality controller configured to manage first media modality of an established communication event, a second media modality controller configured to manage second media modality of the established communication event and a call controller configured to establish the communication event, the method comprising:

• assigning an instance of the first media modality controller to convey first media modality control signals of the communication event to respective first media modality agents of the endpoints without accessing respective second media agents of the endpoints, the instance of the first media modality controller instance being so assigned independently of the second media modality controller and responsive to an instruction received via the network;
• wherein the instance of the first media modality controller is released from said assignment responsive that instance returning a response to the received instruction while the second media modality controller continues to operate in communication the second media agents;
• the method further comprising:
• assigning an instance of the call controller to progress the establishment of the communication event, the call controller instance operating in communication with the call agents of the endpoints following said release of the first media modality controller instance.