Dear
1- You have to get a server and you can create Virtula machine (For Cisco Call manage) and you have to get the CD of CUCM v8.6 or V9.X for Call manager .You can use also as other solution a router wich is supported call manger express software .
2- You have to get a switch (POE) to attach the IP phones , if you do not have POE switch you can get a any switch but you have to get power adapter for Cisco IP phones (when you do not use POE switch).
3- You have to get a cisco voice router (gateway) with 2FXO at least to connect for the PSTN (outgoing calls) .
4- Cisco IP phones any series , or you use Cisco IP communicator *soft phones) and (sip phones "Xlite sftphones").
5-Optional ( you can use other VMware to install Cisco Unityconection). or Voice mail.
6-Optional ( you can use other VMware to install Cisco unified Presence) for availability of users.
Thank you
please rate if this will help