We all know that computers, generally speaking, have not been as reliable as phones. And the fear, uncertainty, and doubt (FUD) surrounding voice over Internet protocol (VoIP) has been, in some cases, justified. However, for VoIP the question now is not whether reliability can be achieved, but rather how much reliability you can expect from the options available to you.
flash data recovery
safely held in local flash memory, and can operate as a standalone PBX if its site is cut off from the IP backbone. It can make besteffort calls on its own, using a failover PSTN trunk if necessary. When switches are added or restored to the network, they and the existing switches at all the sites automatically discover each other and start working together. If a switch providing PSTN access to one site were to fail, its peer switches elsewhere in the WAN would provide alternate PSTN access to the users