These bits and pieces have been taken from TechNet here and put on this page for reference
Hardware Requirements for Skype for Business 2015 Server Front-End Servers
Hardware component | Recommended |
CPU | 64-bit dual processor, hex-core, 2.26 gigahertz (GHz) or higher.Intel Itanium processors are not supported for Skype for Business Server 2015 roles. |
Memory | 32 gigabytes (GB). |
Disk | EITHER:• 8 or more 10000 RPM hard disk drives with at least 72 GB free disk space (two of the disks using RAID 1 and 6 using RAID 10).OR• Solid state drives (SSDs) able to provide the same free space and similar performance to 8 10000 RPM mechanical disk drives. |
Network | 1 dual-port network adapter, 1 Gbps or higher (2 network adapters can be used, but they need to be teamed with a single MAC address and a single IP address). |
Operating System Requirements for Skype for Business Server 2015 Front-End Servers
Windows Server 2012 R2 Enterprise OS with all required updates installed. | Windows Server 2012 R2 Standard OS with all required updates installed. | Windows Server 2012 Datacentre OS with all required updates installed. | Windows Server 2012 Standard OS with all required updates installed. |