Telephone calls to leads outside of the US?

I recently began calling up people who fill out the lead capture form on my website (name, email, phone). I'm based in the US, and calling US numbers is no problem.

But my product is available worldwide and I want to call and speak to international prospects as well. I'm already using Google Voice, but I'm open to other calling solutions.

I have a few questions:

1. Is Google Voice the best solution (on cost & quality) to use for International sales calls to propects? Is Skype to phone a better option?
2. Will the person receiving my call be charged international calling rates? Obviously, I want to avoid this at all costs.
3. Is there an easy way to determine which country a phone number is based in? I can add an additional field for them to enter their country I guess, but wondering if there's a more elegant way (and I want to reduce the number of fields).
4. Any other general tips for calling prospects by phone internationally?

Thanks!

I have had good success using Skype to call internationally. It's very simple to use and the quality of calls is good.

As for the fields, maybe auto-detect their country on your website using javascript and then "fill in" a hidden field on the form. This will be unobtrusive but give you enough information to be able to get their area code to call them.

If you wanted even less technical, just send their IP address with the email and then manually look up their country based on IP address on one of the many websites that do this.

I would strongly recommend looking into companies like BroadVoice. They provide you an internet based phone solution similar to Vonage but their rates seem much better, quality is decent and I know several people that have put Asterisk as a switching for incoming calls as well.