Why are PrimeTel services prepaid?

When you apply for subscription to PrimeTel, you pay for your first month of service in advance, before the installation of the services has taken place. It therefore continues that each month is paid in advance. However, you are only paying for your subscription in advance. Any phone calls you make will appear on your invoice the following month. Whether you pay in advance or after for your subscription, the cost is still always the same.