There are many Long Distance service providers.  The largest (AT&T, WorldCom, Sprint, Qwest) provide relatively high rates.  Smaller ones due to lower overhead offer much better rates while using the same networks.  PowerNet Global, Telna can offer up to 40-60% discount to end-users. You pay less for the same minutes!  For even more savings consider voice over IP (VOIP)

For Direct Dial long distance with heavy international traffic we recommend Telna (total value: low cost, quality, 1 second billing.)

If you want to have unlimited calls from an international location at a fixed price of about $20 from most countries check TelnaMobile (you will get new SIM with low roaming charges).

Calling Cards (also called phone cards or telephone cards) became another distribution channel for selling telecommunication overcapacity. Cards come as pre-paid, post-paid and rechargeable. 

Buying calling card pay attention to card expiration (unless no expiration card), maintenance fees (if any), billing increments (usually 1min, 3 min or even more) and other card features and restrictions.  Usually when you make many short calls cards with short billing increments are your choice. They can come even with 1 sec increments. When you make few long calls then the billing increment is not important, but then the calling rate is important.

Dial Around services require you to dial a dialaround access number before making a call (numbers like 10-10, 1-800, see PIC for the whole list ).  There is no need to change your long distance carrier.  Companies that provide Dial Around services often buy wholesale priced minutes from major telecommunication carriers and resell them at 40% - 60% off. Click Dial Around to compare dial around choices. 

Which one to use?  It depends on countries you call. #1 recommendation - Tel3advantage - no taxes, no fees, no minimums. Other recommendations TelnaMobile (get new SIM with 80% lower roaming charges for international trips), and SpeedyPin.  All these cards have low rates and good or excellent quality, and they sell very well what is another confirmation of their quality.