
Calling cards are often just another form of dial around or call bac. Calling cards are just simple ways of getting a customer to remember their access or PIN numbers. These services come in multiple guises. In principle they are separated into pre-paid and monthly billed services. These terms are self explantory. There after the options are legion. Particular attention should be paid to the billing increments, surcharges, monthly fees and initial set up costs.
The most basic problems occur with phonecard surcharges. This is a charge to physically initiate a call. These can be very high. The rate per minute can appear extremely cheap. However if the call is of short duration the actual cost per minute can be extremely high. You should only buy cards with a surcharge when you are making long duration calls.
International calling cards can also be problematic. Make sure that service is available from the country you intend to call from. Many carriers say their cards are internatinal and in fact only have access from 10 countries. This is a particular problem in the Caribbean islands where service is only available on the major islands.
Exactly as for regular 1010 dialaround and callback, you should take time and care when purchasing a calling card. Careful research will result in a the selection of a reliable carrier.