Please evaluate the following Open Source and Cloud alternatives

Telephony & Cloud Services                                                                         Hybrid Hosted VOIP Providers 
Complete Telephony Engine: Click here
Complete Telephony Engine 		UC Cloud Solutions: Click here
UC Cloud & Premise 		Hosted w/Optional On-Site Appliance: Click here
Cloud Hosted
with on-site failover appliance 		Bigleaf Networks SD-WAN: Click here
SD-WAN IP Failover
with Load Balancing & QoS

Enterprise Operating Systems                                                  Enterprise Management Applications
Comprehensive Linux Server: Click here
Comprehensive Linux Server 		Windows themed Linux Distro: Click here
Windows themed Linux Distro 		Open Broadcaster Software Studio: Click here
Advanced Video Processing
Conferencing & Presentation 		Federated Identity Management: Click here
Federated Identity Management
granular SSO across Enterprise

             Cloud Based DNS                                                                                 Enterprise SIP Servers
Use OpenDNS: Click here
Hardened DNS Service		 Manageable Name Server: Click here
Configurable Name Servers 		Carrier Grade SIP Server: Click Here
Carrier Grade SIP Platform		 Carrier Grade SIP Server: Click here
Carrier Grade SIP Platform