Gracias... Es justo la información que ayer en la noche encontré en otro sitio. Quizá pueda ser interesante para otras personas:
Cita: Another common cable is the flat type often used in RJ11 cables and on ready made flexible telephone extensions. This cable is also not twisted pair and so is not suited to long runs. We only supply a maximum length of 10m for our RJ11 cables to avoid problems but you can probably safely use 20m in most installations.
Saludos y gracias.