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) (10)--served by a wireless telecommunications system. The method includes: establishing a first IP tunnel (20) between the UE (10) and a local access gateway (30) of a visited network in which the UE (10) is roaming, the first tunnel (20) being anchored at the local access gateway (30); establishing a second IP tunnel (22') between the UE (10) and a home gateway (40') of a home network to which the UE (10) belongs, the second tunnel (22') being anchored at the home gateway (40'); receiving data packets at the local access gateway (30) for the UE (10); filtering the packets received at the local access gateway (30) to suitably classify corresponding traffic into one of a plurality of data flows (20a, 20b, . . . 20n) supported within the first tunnel (20) at varying Quality of Service (QoS) levels; receiving data packets at the home gateway (40') for the UE (10); and, filtering the packets received at the home gateway (40') to suitably classify corresponding traffic into one of a plurality of data flows (22a, 22b, . . . 22n) supported within the second tunnel (22') at varying QoS levels.