A method of supporting access to a selected Internet Protocol (IP) multimedia application via an IP Multimedia Subsystem (IMS) is provided for a roaming mobile node (MN)—i.e., user equipment (UE)served by a wireless telecommunications system. The method includes: includes establishing a first IP tunnel between the UE and a local access gateway of a visited network, the first tunnel being anchored at the local access gateway; establishing a second IP tunnel between the UE and a home gateway of a home network, the second tunnel being anchored at the home gateway; receiving data packets at the local access gateway for the UE; filtering the packets received at the local access gateway to suitably classify corresponding traffic into one of a plurality of data flows supported within the first tunnel at varying Quality of Service (QoS) levels; and filtering the received packets.