By Andres Gonzalez, Nadine Schimroszik and Emma-Victoria Farr MADRID (Reuters) – Deutsche Telekom has started the sale process of its towers business and expects indicative offers in the next couple of weeks, three sources with knowledge of the deal said. The German company is working with Goldman Sachs as advisor in the sale of its 40,600 masts, in a deal that could value the business at close to 18 billion euros ($19.9 billion), two of the sources said, speaking on condition of anonymity. A Deutsche Telekom spokesperson said the group was in the process of reviewing several options for the t…