The invention includes methods for converting between a plurality of unicast sessions and a multicast session. A method for converting from unicast sessions to a multicast session includes receiving a request for establishing a unicast session for delivering content to a first client device, generating a multicast session establishment message adapted for establishing a multicast session with the client device for delivering the content to the client device, and generating at least one multicast session join message for the other client devices, the at least one multicast session join message adapted for enabling the other client devices to join the multicast session. The multicast session establishment message is generated using a threshold number of unicast sessions. A method for converting from a multicast session to a unicast session is provided. A method for converting from a plurality of unicast sessions to a plurality of multicast sessions is provided.