Private Sub Worksheet_Change(ByVal Target As Range)
     'MsgBox Target.Count
     'MsgBox Target.Value
     'MsgBox Len(Target.Value)
     'MsgBox InRange(Target, Range("A2:A1000"))
     If InRange(Target, Range("A2:A1000")) And Target.Count = 1 Then
        Call colorValidate(showMatch(Target.Value), Target)
     Else
        'MsgBox "NO SE EJECUTA"
     End If
End Sub
Function InRange(Range1 As Range, Range2 As Range) As Boolean
    'returns True if Range1 is within Range2
    Dim InterSectRange As Range
    Set InterSectRange = Application.Intersect(Range1, Range2)
    InRange = Not InterSectRange Is Nothing
    Set InterSectRange = Nothing
End Function

Function showMatch(ByVal text As String) As Boolean
    Dim regex As Object, str As String
    Set regex = CreateObject("VBScript.RegExp")
    With regex
      .Pattern = "^[3][0-9]{9}$"
    End With
    Debug.Print regex.Test(text)
    showMatch = regex.Test(text)
End Function
Function colorValidate(ByVal resutl As Boolean, ByVal Target As Range)
    If resutl Then
        Target.Interior.Color = RGB(0, 255, 0)
    Else
        Target.Interior.Color = RGB(208, 73, 37)
        MsgBox "VALOR Invalido"
    End If
    
End Function