Credit Card Identification

Public Function CardType(CCNum As String) As String
Dim Header As String
  Select Case Left$(CCNum, 1)
    Case "5"
      Header = Left$(CCNum, 2)
      If Header >= 51 And Header <= 55 And Len(CCNum) = 16 Then
        CardType = "MasterCard"
      End If
    Case "4"
      If Len(CCNum) = 13 Or Len(CCNum) = 16 Then
        CardType = "Visa"
      End If
    Case "3"
      Header = Left$(CCNum, 3)
      If Header >= 340 And Header <= 379 And Len(CCNum) = 15 Then
        CardType = "AMEX"
      End If
      If Header >= 300 And Header <= 305 And Len(CCNum) = 14 Then
        CardType = "Diners Club"
      End If
      If Header >= 360 And Header <= 369 And Len(CCNum) = 14 Then
        CardType = "Diners Club"
      End If
      If Header >= 380 And Header <= 389 And Len(CCNum) = 14 Then
        CardType = "Diners Club"
      End If
      If Header >= 300 And Header <= 399 And Len(CCNum) = 16 Then
        CardType = "JCB"
      End If
    Case "6"
      Header = Left$(CCNum, 4)
      If Header = "6011" And Len(CCNum) = 16 Then
        CardType = "Discover"
      End If
    Case "2"
      Header = Left$(CCNum, 4)
      If (Header = "2014" Or Header = "2149") And Len(CCNum) = 15 Then
        CardType = "enRoute"
      End If
      If Header = "2131" And Len(CCNum) = 15 Then
        CardType = "JCB"
      End If
    Case "1"
      Header = Left$(CCNum, 4)
      If Header = "1800" And Len(CCNum) = 15 Then
        CardType = "JCB"
      End If
  End Select
  If CardType = "" Then CardType = "Unknown"
End Function