I worked in Africa, albeit 35 years ago, dealing with aircraft flying into desert oil camps. Once they were about 20 miles out they changed to HF communication and maintained that whilst in the desert. There was no ATC, as such, because it was in uncontrolled airspace. We provided an FIS and alerting service and they would transmit "ops normal" every 30 mins and advise when landing and departing.
Things are probably differentnowadays although the above may be close to the truth in some areas still.