The study of mobile Internet telephony

We attempt to integrate the technology of VoIP (voice over IP) and mobile computing together so that a mobile Internet telephony system (MVoIP) can be built on an integrated roaming environment of different networks. In order to support the mobility of the system, the handset of the MVoIP system should have multiple adapters, which have different communication area coverage ranges. The adapters should be given the ability to be used in a complementary fashion. The adapters used in this paper are those for an Ethernet, a wireless local area network and a cellular telephone network. The inherited problems with VoIP are not addressed, but the new problems with MVoIP are emphasized. These new problems are: (1) how to use the adapters in a complementary way so that the mobile area can be as large as possible, and (2) how to reduce the time delay of handoff so that the voice transmission can be smooth. The solutions for solving these two problems are described in detail.