VoIP standards define numerous signaling protocols that are used to set up and carry out the calls, transmit information required to identify and locate remote callers, and negotiate carrier and endpoint capabilities. Different companies developed numerous different signaling protocols within the VoIP scope. SIP and H.323 are dominating the VoIP arena as the most commonly used signaling protocols.
Choosing one signaling protocol over another when developing a VoIP solution is a matter of a set service requirement and the choice of equipment. SIP is commonly chosen among the full-scale VoIP carriers to make use of the abundance of SIP-compatible VoIP devices including the numerous inexpensive SIP phones and adapters. When multimedia communication over IP networks is required, including video conferencing and data calls in addition to audio transmission, H.323 becomes the natural choice.
As defined by the scope of the signaling protocols, there are numerous potential problems that may arise because of compatibility or networking problems. The dreadful "unable to connect" problem lies frequently in the domain of signaling protocols. The two peers, once located, may be unable to connect because of compatibility problems between the two endpoints (various SIP implementations are especially prone to this problem) as well as the lack of the required features such as conference calling in one of the connecting devices.
A network analyzer should recognize and support both SIP and H.323 signaling protocols, allowing the detection of problems that occur on the signaling phase early during the implementation of a VoIP system. Throughout this white paper, we'll be illustrating the problems and solutions with the help of CommView and CommView for WiFi, software-based network analyzers for wired and wireless networks that include a VoIP analysis engine.