Olá,
In the Azores we have Santa Maria Oceanic Airspace Center (OACC) which uses HF frequencies to controll all traffic above and outside the limits of Santa Maria Terminal Area (TMA), which controlls just the airspace of all 9 islands of the Azores. Then, we have the normal towers and approach stations.
Both in Santa Maria OACC, Santa Maria TMA and 8 of 9 airports, no radar is used, but the procedures you have to follow on each airspace is diferent. For Santa Maria OACC you need to follow Oceanic procedures but for the TMA it's the same as you were flying anywhere with radar with the exeption the controller is unable to see you, so, he will depnd on all of your reported estimated times to the fix's and present position from VORs, Fixs, etc...
Currently, the only island where radar is used is Terceira, which is a Portuguese Air Force base.
Was I clear enought? The Azorean airspace is complicated, i know! :]
I made this image... maybe it will help you!

Red stuff are the AFIS,
White - Tower
Green - Approach
João