A method of completing RCS file transfer. The method comprises receiving a first SIP message comprising a first URL designating a file stored in a first message store in a first network by an RCS server in a second network; sending the first URL by the RCS server to a second message store in the second network; identifying a second URL by the second message store, wherein the second URL is to be associated with the first URL by a proxy server; sending the first URL and the second URL by the second message store to the proxy server; sending the second URL by the second message store to the RCS server; and sending a second SIP message comprising the second URL by the RCS server to a communication device, whereby the communication device is enabled to request a file from the proxy based on the second URL.