What you need is different than has been offered by the existing HA capability. With the existing capability, call drops weren’t prevented - calls drop in the event of server death, but new calls, via the second server, can be established quickly. Live call fail-over is a whole other matter.
You’re not going to get where you want to go without spending a sh*t-ton of money. In order for this to work, you’ll have to have duplicate data paths through disparate servers running on different hardware platforms through disassociated network infrastructures.
You will need the following:
- A duplicate server running your call up to the point that it connects to the phone,
- A way to redirect the phone to a new server seamlessly.
- An infrastructure provider that can dual route all of your calls to multiple servers in different locations.
- A way, at the phone, to dedupe packets as they are processed through the network, especially as servers add and drop.
I know a system like this. It has about 200 nodes. The total cost of the system was well over $2B. The system is over 2M lines of assembly language code. The call paths are managed through dedicated communication trunks that are managed centrally with no other purpose but managing the messaging network. There is a move afoot to replace it - the price tag on the replace is about $20B so far.
Thanks for the input. Good to know!