Voip Research - open to bidding

Hello Ben, I live in Trinidad and Tobago (868) area Code. I would like to install a basic VOIP system that would also allow me to keep my existing landline number. The voice system must have call forwarding features. That is, after convert my number to a VOIP number I must be able to forward all calls to that number to another number. I need your recommendations to achieve this as well point me to purchase options.