Darren,

You can look for Communications Manager compatibility matrixs when you can find hardware and software versions.

In this link you can find hardware compatibility:

http://www.cisco.com/en/US/prod/collateral/voicesw/ps6790/ps5748/ps378/prod_brochure0900aecd8062a4f9.html

I this other you can find hardware and OS compatibility:

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/compat/mcs-server-os-0711.xls

In thi sother one, you can find all Callmaanger compatibility and versions: OS, phones, gateways, related products, etc.:

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/compat/ccmcompmatr.html

You can access all this pages from this URL:

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_device_support_tables_list.html

As a fast explanation, CallManager 4.X runs on Windows 2000, except version 4.3 that runs on 2003. Versions 5 and 6 uses Linux.

Hope this helps,

Juan Luis

Regarding