Abstract: Systems and methods are provided for real-time communication (e.g., fax, voice, video) via an IP Network even if a firewall or other restriction element is present or encountered. The real-time nature of the communication is ensured by preestablishing a communication session between a transfer client and a transfer server, between which the firewall or other restriction element is located. Following the preestablishment of the communication session, transmission control messages are exchanged between the transfer server and the transfer client via the preestablished communication session. The preestablished communication session prevents the firewall or other restriction element from blocking or delaying traffic (e.g., fax, voice, video traffic). The preestablished communication session establishes a full duplex communication link without restriction of or by the firewall or other communication restriction element.