Dim objMapiSession As Session
Dim objAddrList As Object
Dim objAddressEntry As Mapi.AddressEntry

    Set objMapiSession = CreateObject("MAPI.Session")
    
    objMapiSession.Logon profilename:="user", profilePassword:="xxxx"
    
    Set objAddrList = objMapiSession.AddressLists("Global Address 
List").AddressEntries
   
    Set objFilter = objAddrList.Filter
    objFilter.Fields.Add CdoPR_ACCOUNT, "user"
    Set objAddressEntry = objAddrList(1)

    objAddressEntry.Fields(CdoPR_BUSINESS_TELEPHONE_NUMBER) = "311"
    objAddressEntry.Update