 | Reliability |
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| VoIP Network Reliability |
In order for VoIP usage to exceed PSTN usage, the IP network must become as reliable as the PSTN network today. If VoIP networks do not become as reliable, they will not have customers for long. With such an essential service as telephony, businesses and individuals will not tolerate outages for any reason. Reliability can be achieved through two different means, both of which are needed to bring about reliable VoIP networks. They are redundant equipment and redundant or multiple network interconnections. | | | | An obvious approach to reliability is redundancy especially in equipment. Reliable VoIP equipment will, by necessity, have to be redundant. Unlike data, telephony calls are "connection-oriented" and "stateful," that is, a telephony call is a connection between at least two entities that must be maintained for the duration of the call and the call must proceed through various "states" during setup, conversation, and tear down. Preservation of this information is necessary to maintain a voice call throughout its life even if a piece of equipment breaks down. This means that redundant systems that maintain call state and processing information between them are necessary for a reliable network. VoIP networks will have to have redundancy in their gateways, softswitches, etc. that can preserve and maintain call information even during equipment failures. | | | | The second, less-obvious requirement for reliability is interconnection with multiple PSTN and IP networks. If a gateway has redundant components but only a single WAN interface, or its path to the IP network is through a single router, and the WAN interface or IP network equipment goes down, redundancy within a VoIP gateway will do nothing to ensure the continued operation of the VoIP network. Since the IP network is inherently unreliable and IP protocols were not designed for redundancy, the only way a network breakdown can be handled is to interface with multiple IP networks. This is also true for PSTN networks. Failure to have multiple networks may cause a VoIP carrier to quickly lose customers, and perhaps its entire business if network breakdowns occur frequently. | | | | To circumvent network outages, the VoIP carrier must use VoIP equipment that supports at least two separate and distinct IP carrier networks, at least two PSTN networks, and can route to any network based upon least-cost routing and/or carrier outages. This solution can be two interfaces to two different points of presence into a single IP carrier or two completely separate interfaces into two different IP carriers. The same is true for PSTN interfaces. The second approach has the added advantage of selecting the one with the lowest cost to a particular destination as the primary carrier. Without the ability to interface with two or more PSTN carriers and two or more IP network carriers, no VoIP carrier will have true network reliability. This lack of ability becomes painfully evident the first time the VoIP carrier's network, whether PSTN or IP, goes down, and the carrier subsequently loses customers. | | | |
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