For very heavy calling, consider an unlimited plan from Verizon or ATT.

For long calls within the US, consider USADatanet. They have a plan where it is 10 cents a minute up to a MAX of 99 cents per call. but if you do lots of calls, I think a flat plan is better.

Otherwise, I like onesuite, which is 2.9 cents a minute for long distance, 2.5 cents if you use the local access numbers.

I am going to try a VoIP service-- Vonage (www.vonage.com) and forego a traditional landline, with their excessive surcharges. They have a plan for 29.99 a month with unlimited calling throughout the US and Canada, with voicemail, caller ID, call waiting, etc. That uses your home's broadband connection to route the calls. You use your regular phone. I will probably stick with the inexpensive 14.99 plan for now.

Just some thoughts.