You will need to configure the Greetings Administrator in order for users to dial in, authenticate, and then administer Call Handlers to which they have access.
First though, you need to confirm whether you have Unity or Unity Connection as I don't believe Unity Connection supports the use of Distribution Lists for Call Handler owner assignment (unless you have a legacy version like 1.x or 2.x). Instead, Unity Connection users must be assigned the Greetings Administrator role and then be assigned permissions to each call handler they can administer on an individual basis.
Unity Connection setup for CUGA is here: http://www.cisco.com/en/US/docs/voice_ip_comm/connection/7x/administration/guide/7xcucsag150.html#wp1049924
The standard Unity setup is here: http://www.cisco.com/en/US/docs/voice_ip_comm/unity/5x/administration/guide/dom/5xcusag250d.html
Hailey
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