Most of Cisco's applications come with built-in demo licenses. For instance, CUCM/IMP, CUC, CER, UCCX, (and the list goes on) will all work without limitation for a "demo period" which ranges from 60-180 days. You can request extensions to the demo license on the Cisco Licensing Portal.
The trick with all of this is that you have to lay your hands on the installation ISOs for these products and that is a little trickier. Depending on your status with Cisco, you may be able to purchase a "Not For Resale" kit, which contains a full set of UC software.
If you web search for these things (Cisco Demo License and Cisco NFR kit) you should find information and instructions.
HTH
Maren
