Mobile telecommunication systems such as General Packet Radio Service (GPRS) and Universal Mobile Telecommunications System (UMTS) provide packet-switched service for mobile terminals. 3GPP Release 4 and Release 5 further offer packet voice over a GPRS/UMTS infrastructure so that IP based communications between mobile to mobile is expected to be one of the major traffic types in the future 3G All-IP network. Considering packet communications between mobile to mobile in GPRS/UMTS networks, every packet has to go to Gateway GPRS Support Node (GGSN) and then can be delivered to the destinations according to the current GPRS/UMTS specifications. However, packet delivery through GGSN is not efficient if two mobile nodes are in the same base station or the same routing area. This design degrades overall system performance and introduces extra delay of mobile-to-mobile communications. This paper investigates packet routing/forwarding procedures and proposes a novel approach to improve mobile-to-mobile packet delivery in GPRS/UMTS networks. Simulations results demonstrate that end-to-end latency can be reduced significantly in GPRS/UMTS networks.