Lost manual for DECT 6.0 phone. Hopping to download manual. Don't know how to get voice mail from unit.

You can find a users manual at: http://www.uniden.com/index/manuals_results.cfm?cat=1
You will have to know what model it is, usually you can find that out by looking at the bottom of the base, or on the underside of the battery cover, or under the battery.
As for getting the voice mail, if you use your providers voice mail service, usually you have to dial something like *99 or *00. You would have to contact your phone provider and find out what the number is to reach your voice mail.