I've searched back in the VoiceOps archive for a discussion about redundancy, and it has been a while. I wanted to spark a useful discussion for the list, and hopefully figure out one issue we're having. We use a SIP provider that connects to our IP-PBX in our datacenter. We have standard redundancy within our PBX infrastructure, but we want to build out redundancy for if our SIP provider has an issue reaching our PBX (could be DNS issues, network issues, primary & backup datacenters down, etc.). If our SIP provider is unable to reach our PBX, they offer a 'failover route' where it can route to a standard 11-digit DID. For individual employees' DIDs, we're just routing directly to their cell number. The issue is routing our high-volume DIDs -- the main IVR, the call groups, etc -- to simultaneously ring a group of cell numbers.
From our research, the best bet seems to be to utilize eVoice <https://www.evoice.com/feature/included/simultaneous-ring>, and setup up a new (unpublished) DID to ring ~15 cell phones using up their 'Simultaneous Ring,' and then forward our high-volume DIDs to the new eVoice DID.
Does anybody have experience with this? Am I going about this in an asinine way? Is there a better vendor? Are there other ways that you've built out inbound redundancy for VoIP solutions you've deployed? Thanks, Jacob P.S. To add to discussion - While our SIP provider were to be disconnected from our PBX, lost inbound faxes are also a concern. I'd then use something like eFax <https://www.efax.com.au/web-fax-pricing> to take the inbound faxes to a distribution group email (after testing it works while forwarded from our SIP provider, who does use T.38), by setting a backup route for our fax DIDs to hit our new eFax DID. These two measures would ensure minimal missed calls/faxes while critical infrastructure was down. eVoice Link: https://www.evoice.com/feature/included/simultaneous-ring eFax Link: https://www.efax.com/features