No CAL required.
Per http://www.microsoft.com/india/sam/lic_cal.mspx,
If your company's workstations are networked, you will utilize a network
server and the workstations on the network will access that server(s)
software to perform certain functions such as file and print sharing. In
order to legally access this server software, a client access license
or CAL may be required.
So the keywords are:
- Workstation (Windows XP, Windows 7, Samba Client, etc.)
- File and Print Sharing
CUCM does NOT fall into either one of them.
Michael
http://htluo.blogspot.com