Can I deploy High Availability on a VPS Service?

Not at this moment. High Availability with VitalPBX is designed for a Data Center environment, where you have full control of the network and installation process. Since you require to have three IP addresses, and need to make some customizations at the moment of installation. You can deploy High Availability on a Virtual or Physical Environment no problem, as long as you have control over network and installation. The machines could be on different locations, as long as they belong to a connected network where the can freely see each other for configuration replication.