With the spread of mobile devices, there is a growing demand for direct communication between users. However, under recent complex IP networks, it is extremely hard to establish a direct connection between devices. In order to solve the problem, authors have been proposing a new end-to-end communication architecture called "Network Traversal with Mobility" (NTMobile). In NTMobile, applications in the mobile device establish an end-to-end connection by using virtual IPv4/IPv6 addresses in the NTMobile network independent from real IP networks. In this demo, we will show that Android smartphones can make free communication with each other without any constraint such as an NAT traversal problem in IPv4 networks and incompatibility between IPv4 and IPv6 architectures.