Patent ID: 7454510

Claim:
A method in a proxy engine to establish a media session for sending a media stream from a sender to a recipient, the sender and the proxy engine being within a first address space with a firewall at a network boundary to a second address space, comprising the steps of: allocating address and port combinations of the firewall to an address resource pool; determining whether the media stream crosses the network boundary between the first address space and the second address space; and if the media stream crosses the network boundary: identifying a media relay that is within the first address space to relay the media stream across the network boundary; commanding the identified media relay to reserve a media path having at least one port of the firewall for the media, the media path having a reserved public address identifier; and if the at least one port is reserved: modifying a session description such that an address identifiers for the media stream is changed to the reserved public address identifiers; sending the session description in a message to the recipient; notifying the sender of a private address identifier of the media relay and a public address identifier of the recipient; and notifying the media relay to relay the media stream sent via the reserved public address identifier to the private address identifier of the sender and to relay the media stream sent via the private address identifier of the media stream to the public address identifier of the recipient.