Compare Unified Communications Solutions

I have a legacy PBX that is out of warranty I have experienced a recent outage and want a more relaible solution I have a service contract expiring soon and want to explore my options I am paying too much for my current solution I am not satisfied with the quality of technical support I receive I have outgrown my current system and need something that scales I no longer want to be responsible for managing my telephony environment I have too many disparate systems and want to consolidate to a cloud-based solution