Can we use VoIP and a PSTN PBX with each other? When there is a problem with the PBX, will the VoIP still work and our calls still connect?
Yes -- depending on the equipment, but all will have some type of gateway. These systems are called hybrids. As for the failover, if one or the other side fails, it depends on the type of failure and how your equipment vendor handles these services.
This was first published in September 2006