H.323 is currently the industry’s predominant standard for offering multimedia services over IP networks, although the session initiation protocol (SIP) continues to generate significant interest in the market-place for rendezvous-based real-time applications. With its greater maturity, H.323-based equipment continues to be deployed in operational networks. However, with the advent of SIP-based...

——VoIP over Wireless LANs is greatly affected by path-loss, RF interference and other sources of signal attenuation in addition to network congestion. The primary factors involved in effective real-time communication, namely delay and loss, must be within certain controlled limits in such a scenario. Wireless LAN Access Points must, therefore, act in tune with the codecs to ensure high quality ...

Voice over IP (VoIP) is one of the most popular Internet applications. Many VoIP protocols (e.g. SIP) are based on a central-server scheme in which a caller needs to query the central server first for the callee’s information (e.g. IP address) before it can connect to them. However, such a centralized architecture has some drawbacks, such as an unbalanced load and a single point of the failure....

SIP is promising for VoIP signaling to support personal mobility. In this paper, we introduce and compare single registration (SR) and multiple registration (MR) for personal mobility. The SR scheme can not support personal mobility without user’s assistance. In contrast, the MR scheme supports personal mobility inherently using sequential search or pure parallel search. Sequential search may s...

The Session Initiation Protocol (SIP) is at the root of many sessions-based applications such as VoIP and media streaming that are used by a growing number of users and organizations. The increase of the availability and use of such applications calls for careful attention to the possibility of transferring malformed, incorrect, or malicious SIP messages as they can cause problems ranging from ...

The steady improvements in the networking infrastructure and ever increasing broadband penetration has fueled the resurgence of voice-over-IP (VoIP). One of the important contributors to this growth has also been the development and wide acceptance of the session initiation protocol (SIP). However, the current usage of SIP requires a per-application deployment (each application using its own SI...

The NTC has contracted Chula UniSearch, a consulting arm of Chulalongkorn University (CU), led by Dr. Supavadee Aramvith and Dr. Chaodit Aswakul, to operate the project which is participated by CAT Telecom, Samart Telecom, AIS, NEC, Rohde&Schwarz, FORTH and ADC Communications. NGN technologies such as 3G, Wi-Max, VoIP, SIP server/Soft switch, VoD and FTTH are evaluated in the project along with...