When a Rich Communications Services (RCS) data file is to be provided to a terminating user equipment (UE) that is on a different mobile communications network than an originating UE, the network address, or uniform resource locator (URL), of the RCS data file may be modified to indicate that the RCS data file is to traverse a network-to-network interface (NNI). An RCS system on the originating mobile communications network may identify if the terminating UE is on the same or different mobile communications network. If the terminating UE is on a different mobile communications network, then the RCS system may modify the URL to indicate the originating and terminating mobile communications networks and send the URL to an RCS system of the terminating mobile communications network. The modified URL enables retrieval of the RCS data file network by a content system of the terminating mobile communications network.