Enabling a feature of an application during a communication event by receiving a certificate

Disclosed is a method of enabling a feature on a user's terminal, that is required to process received data. The method starts by determining that a user's terminal requires the use of a feature, that is otherwise not enabled, for processing data during a communication event. Next, a certificate is retrieved enabling the use of the feature at the user terminal and the feature is used to process the sent data. The user's terminal may request the certificate from a node on the network, the node determining, based on the request, whether the use of the feature at the terminal is authorized and if so sending the certificate. The certificate may include a signature authenticating the certificate, an identifier of the feature to be enabled, the user, the terminal and parameters relating to the feature. The feature may be permanently or temporarily enabled. The feature may be codec, a multiparty video session or a screen sharing session.