Required software development freelancer for Asterisk HA cluster without call disconnect job

I have Two asterisks servers based on Raspberry PI 4 (Freepbx) I want to make a HA mode for both servers and it is must be keep in focus that when primary server goes down and secondary will take place on that case running calls should not be disconnect and all the data must be sync with both servers like call recording, voicemails, IVR and any configuration means everything on primary server must be on secondary server.

all the running call should remain continue.
What I am looking from your end is below
1. Two asterisk server real time HA mode with out current call disconnection.
2. Step by Step configuration guide in word doc so that later on when required we can replicate same configuration.
3. I already check so many portals but all have 1 to 10 seconds downtime and all calls drop during second server takes place, so make sure i want real time HA mode.

Skills & Expertise Required

software development