I got Uniden DECT 6.0 and have a voice mail with a "M" displayed on the right top corner of the phone display. Please let me know how to listen to the voice mail.

Les,

If you want to delete the actual voice mails, you have to go through your phone company (using their keypad commands) since voice mail is only accessible through your phone (but the voice mail messages are stored through your phone company provider).

Info from the Uniden DECT 6.0 6035 Manual:

Using the Voice Mail Service If you subscribe to a voice mail service, you can use your phone to access your voice mailbox. The new message LED on the handset ?ashes and VM appears in the handset display whenever you have messages waiting in yourvoice mailbox. When you subscribe to the service, your voice mail provider provides you with the access number and the required voice mail signaling tone. You can use your phonebook to store the access number.

Resetting the Voice Message Waiting Indicator

When you receive a new voice mail message, the new message LED on the top of the handset ?ashes and
appears in the handset display. In the event your message alert tone gets out of sync with your phone company's voice messaging system, you can reset back to its original "no messages waiting" state. To reset, press and hold [?nd hs] on the base for ?ve seconds. A beep sounds and the message alert tone is reset.

Here is the manual:
Uniden 6035 1 Owner Manual

If you subscribe to a voice mail service, you can use your phone to access your voice mailbox. The new message
LED on the handset flashes and appears in the handset display whenever you have messages waiting in your
voice mailbox. When you subscribe to the service, your voice mail provider provides you with the access number
and the required voice mail signaling tone. You can use your phonebook to store the access number

Since you declined to specify the model of your Uniden DECT 6.0 system, I can only suggest that you select it from the list beginning here to download a copy of the manual.

Select the model of your Uniden DECT 6.0 phone from the list beginning at
http://www.uniden.com/owners-manuals/dect-phones/scat/dectphones_mnl/
to get the manual.

If it doesn't, you can reset it: With the phone in standby, open the
menu and select Global Setup; select VMWI Reset, then select Yes.

Select your model from the list at
http://www.uniden.com/index/manuals_results.cfm?cat=59

What model Uniden DECT 6.0 phone/answering machine?

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.

on the base set, press and hold the voice mail 1 button. You will get a message clear voice mail indication? hit the sel/save button to the left of the display.

poof! message gone