NT User Name to get Outlook information

I am trying to use the NT id of the person logged into the computer to sign an email. I am trying to translate the ID into the First Name, Last Name & Telephone Number of the person (all are stored on the company address book). I use the below code to get the NT User ID:

Private Declare Function GetUserName Lib "advapi32.dll" _
    Alias "GetUserNameA" ( _
    ByVal lpBuffer As String, _
    ByRef nSize As Long) As Long


Public Property Get username() As String
    Dim stBuff As String * 255, lAPIResult As Long
    Dim lBuffLen As Long
    
    lBuffLen = 255
    
    lAPIResult = GetUserName(stBuff, lBuffLen)
    
    If lBuffLen > 0 Then username = Left(stBuff, lBuffLen - 1)
        
End Property

How do I take the username and look up the contact infor from the outlook address book?

Re: NT User Name to get Outlook information

I was able to find some code to download the entire address book but nothing to find info on just one person. Specifically, I am looking for the first and last name and the telephone number