A method is disclosed that enables the transmission of media and signaling packets in a Proxy Mobile Internet Protocol-based (PMIP-based) network. A mobile access gateway is enhanced to differentiate between different types of packet traffic and to act as a Session Initiation Protocol (SIP) proxy on behalf of a mobile node. For example, the gateway is able to handle quality-of-service-sensitive (QoS-sensitive) traffic such as voice or video media packets differently from QoS-insensitive traffic such as SIP signaling packets. In the case of traffic packets that are not QoS-sensitive, the gateway engages standard PMIPv6 procedure. In the case of traffic packets that are in fact QoS-sensitive, the gateway acts as a SIP proxy for each mobile node attached to it, thereby avoiding tunneling of the packets between the gateway and the mobile node's local mobility anchor, and thereby reducing the amount of delay that affects the packets.