1) and 3) below are applicable to both CentOS and Ubuntu VPS.
2) is applicable to CentOS VPS
4 & 5) are applicable to Ubuntu VPS
1) installing and configuring CSF on both of them. I think CentOS has its own but we need to remove it and install CSF
2) Setting firewall rules for CentOS VPS in security groups that will secure it further (no functionality should suffer due to this)
3) Disabling login through password authentication (i think you had enabled it for the purpose of this work). This is because I dont need to enter password and no-one other than me will need to login. (Provide me instruction of how to enable it in case if I need to give it to someone such as yourself)
4) Configuring BBB for inbound number dialling with right voice prompts & access code (BBB docs has nicely described this. You may need to check the APIs of the trunk provider to configure it)
5) Help resolve this issue on Google Chrome Detected the following WebRTC issue: Error 1004: Failure on call (reason=Incompatible SDP). Do you want to try Flash instead?". I get this when I try to connect to Audio bridge with Mic of BBB training interface via my Google Chrome browser. I think you may also get same error if you try with mic. Firefox is fine.
Both VPS are live and being used by users. So safety of services is more important. So appreciate if you dont let any of the services impacted. I'll provider test account to check things.
Please provide your fixed price quote.