Study On LAN Phone Terminal

With the rapid development of network technology, multimedia communications beginto play a more important role in this area. Nowadays, the voice transmission on Internet isquite feasible based on the progress of real-time transmission technology. It is possible for IPphone successfully entered the domain of traditional telecommunications. VOIP is such atechnology that could accomplish speech-communication on computer networks.Compare to traditional telephone, there are many advantages in using IP phone. One ofthem is that the existing computer network could be utilized in a more effective way, and thecost of communications could be remarkably reduced. And along with the expansibility ofInternet, more and more VOIP services with good quality could be provided.In this scheme, the architecture of hardware software of a IP phone was studied andreported in this paper. In this scheme, the ARM9and μClinux were chosen to construct thebasic platform, and the voice-data sampling was accomplished by the audio processor chipUDA1341. RTP and UDP protocol were used to pack and transmit audio data for getting agood Real-time effect.Mainly, three questions were discussed in this paper:1. Development methods of embedded linux OS, the configuration of linux kernel anddownloading of root-file system;2. Driver programming under linux OS, voice sampling through audio processorUDA1341;3. Packaging voice data into an RTP packet by using the standard library of JRTPLIB,and transmit it via the internet by UDP protocol.