H.-P. LinH.-Y. HsiehHUNG-YUN HSIEH2018-09-102018-09-102010-05http://scholars.lib.ntu.edu.tw/handle/123456789/359552As IP telephony gains more popularity, interworking with conventional PSTN telephony has also gained more importance. In particular, an increasing number of new telephony services now involves both packet-switched (IP telephony) and circuit-switched (PSTN telephony) voice legs in one call session. One common problem that arises for enabling such new services is the need for synchronization of voice streams that traverse through heterogeneous telephony systems. In this paper, we first identify the key role of voice synchronization across heterogeneous telephony systems for services such as seamless handover between WLAN and cellular networks and multi-party audio conferencing with video overlay. We then explain the challenges in synchronizing circuit-switched and packet-switched voice streams, including codec distortion, packet losses, line noises, and overlapping utterances. To achieve voice synchronization, we proceed to investigate three different approaches based on digital speech processing techniques in the waveform, cepstrum, and spectrum domains. Finally, we compare the performance benefits and tradeoffs of different approaches, thus motivating further research along this direction. ©2010 IEEE.[SDGs]SDG16Audio conferencing; Cellular network; Cepstrum; Common problems; Interworking; IP telephony; Line noise; New services; Packet-switched; Performance benefits; Seamless Handover; Synchronizing circuits; Telephony services; Telephony systems; Voice stream; Wave forms; Audio systems; Cellular neural networks; Computer crime; Internet telephony; Mobile telecommunication systems; Packet networks; Speech processing; Synchronization; Telephone systems; Video conferencing; Wireless local area networks (WLAN); Voice/data communication systemsconference paper10.1109/ICC.2010.55024332-s2.0-77955364162