'Determina si hay conexion via modem
Public Declare Function RasEnumConnections Lib "RasApi32.dll" Alias "RasEnumConnectionsA" (lpRasCon As Any, lpcb As Long, lpcConnections As Long) As Long
Public Declare Function RasGetConnectStatus Lib "RasApi32.dll" Alias "RasGetConnectStatusA" (ByVal hRasCon As Long, lpStatus As Any) As Long
Public Const RAS95_MaxEntryName = 256
Public Const RAS95_MaxDeviceType = 16
Public Const RAS95_MaxDeviceName = 32
Public Type RASCONN95
       dwSize As Long
       hRasCon As Long
       szEntryName(RAS95_MaxEntryName) As Byte
       szDeviceType(RAS95_MaxDeviceType) As Byte
       szDeviceName(RAS95_MaxDeviceName) As Byte
End Type
Public Type RASCONNSTATUS95
       dwSize As Long
       RasConnState As Long
       dwError As Long
       szDeviceType(RAS95_MaxDeviceType) As Byte
       szDeviceName(RAS95_MaxDeviceName) As Byte
End Type

Public Function IsModemConnected() As Boolean
    Dim TRasCon(255) As RASCONN95
    Dim lg As Long
    Dim lpcon As Long
    Dim RetVal As Long
    Dim Tstatus As RASCONNSTATUS95
    TRasCon(0).dwSize = 412
    lg = 256 * TRasCon(0).dwSize
    RetVal = RasEnumConnections(TRasCon(0), lg, lpcon)
    If RetVal <> 0 Then
         MsgBox "ERROR"
         Exit Function
    End If
    
    Tstatus.dwSize = 160
    RetVal = RasGetConnectStatus(TRasCon(0).hRasCon, Tstatus)
    If Tstatus.RasConnState = &H2000 Then
      IsModemConnected = True
     Else
      IsModemConnected = False
    End If
End Function