My best bet in a country like Sudan is to buy a sat phone before leaving.
Phone: Thuraya Satellite Phone/GSM = $1,275.00
Accessories: Portable phone charger: $112.50
Spare battery: $60.00
Portable computer charger: $100.00
Plane Ticket: Round trip cost: $2,122.00
Lodging: $85 per night. Cost: $7,225.00
Food: $500.00
Car: $500.00
Visa: $221.00
Total For Three Months In South Sudan: $12,115.50
Sudanation 