It is common knowledge that the legacy PBX is limited in its ability to have a backup solution other than another legacy PBX on the same premises. This can also be true of an IP-PBX if the backup call manager is on the same site as the primary call manager and the PSTN terminations are on the unavailable site. Power loss, fire, flood, tornado, police emergency or any other similar event can make the facility housing the PBX/IP-PBX not available, and therefore telephone service is lost.
A service already exists that can route calls from the PSTN to alternate numbers. It is called Direct Termination Overflow (DTO). DTO is a feature whereby a call to be terminated on a phone trunk (analog, T1, PRI) can be forwarded to a 10-digit phone number if the trunks are full or otherwise not available. DTO can automatically redirect calls to any telephone number. This can be an alternate office, an answering service, a residence or cell phone or a PBX backup service. Using DTOs can be part of the enterprise's disaster recovery plans.
Another option is the cloud: A company called Virtual PBX has come up with a solution that requires no equipment at the customer site and no capital investment; instead, it uses DTO connections. Thus the loss of PBX access for the inbound calls can be alleviated by rerouting the calls to a cloud/hosted PBX service.
Why not just let employees rely on cell phones in case of a PBX failure? Because when the PBX becomes unavailable, cell phones may work for outbound calls, but what about trying to handle the inbound call traffic? The enterprise needs a rapid, orderly transition to a backup service.
I spoke to Greg Brashier, CMO for Virtual PBX, about their offering, called PBX Parachute, to solve the disaster recovery problem. Greg noted that it is common that most medium to large scale enterprises still have a PBX. The PBX termination to the PSTN is hard-wired. Therefore the loss of the PBX means service is lost unless the inbound calls can be rerouted to alternate phone numbers. That is fine for answering a call, but the inbound call cannot access any of the PBX functions. Connecting the inbound calls to a mirror image system that emulates and is configured like the inaccessible PBX is ideal. The inbound caller would not see any difference. Further, those employees and agents answering calls at the alternate phone numbers can place outbound calls with the services that were on the unavailable PBX.
Combining DTO with the call rerouting to a cloud/hosted PBX site can provide near-instant backup. The backup service should be at some distance from the enterprise to ensure that the same disaster experienced by the enterprise does not affect the cloud/hosted site and does not affect the PSTN and the PSTN terminations. The backup site should have its own disaster recovery plan as well.
But this not the end. The enterprise's PBX will have continually changing active and inactive phone numbers and changing privileges and restrictions. The backup service should also make these changes instantly.
Greg pointed out that the backup service can be for all or just some of the PBX extensions. The inbound calls, using DTO, can be rerouted to an off-site IVR to handle some of the calls. Another aspect is that the backup service does not depend on the Internet to handle the inbound calls, providing a higher level of reliability for the enterprise.
