Hi Julio -
You'll want to check a couple of resource links:
- Upgrade Unity to current shipped version http://www.cisco.com/en/US/docs/voice_ip_comm/unity/42/upgrade/guide/ex/ru_010.html
- Release notes for the specific version you want to upgrade to - http://www.cisco.com/en/US/products/sw/voicesw/ps2237/prod_release_notes_list.html
Most often, the upgrade includes a change in Unity TSP. For example, if you upgrade from 4.2(1) to 5.x, the 5.x install brings in a new TSP. You don't need to perform this step separately or in advance. But, read the release notes for OS or Exchange version requirements, including any license file upgrades you may need to get.
- Compatibility matrix or integration documents for the PBX you are using, i.e. Cisco Unified Communication Manager or Avaya's PBX varieties.
Ginger