You will need a couple of Callmanager System 4.13,4.2 or 4.3 if you want to stay Windows based. If Linux you will need 5.X or 6.X system. You will need a Cisco Voicemail system 4.X. I would recommend a 3560 or 3570 PoE switch. You wlll need a couple of 28XX Router for Gateway and simulating IP calls across a point-to-point WAN. Make sure you get a couple of MFT-2T1 cards and some DSP's with the routers. I would also recommend a ATA-186/188. And of course you will need a few IP phones, I would recommend 7941, 7961's.
If you want to simulate wireless I would recommend a Cisco .11b/g access point and a 7920/21 phone. This should get you started.