 Mexican broadcaster Televisa said on Sunday it will start offering mobile phone service, a bid to challenge billionaire Carlos Slims America Movil, which has long dominated the countrys telecommunications market. Rather than building infrastructure, Televisa will operate as a mobile virtual network operator, or MVNO, and begin by offering service to existing customers of its cable and home internet packages, sold under its Izzi brand. Televisa originally planned to roll out the service in September, Izzi Chief Executive Salvi Folch said in an interview. 