International calls costs

I recently noticed my brothers bt bill a whopping £90 a month. He's an online teacher and teaches mainly forgein students. He doesn't have unlimited broadband and pays line rental monthly + International freedom for £8.50. (The first hour is free and you can disconnect and reconnect if you need for longer) and around 28 hours per week. He thinks that it's worth paying because of the cost of international freedom. I disagree, I'm struggling to find a good comparisons site that shows international prices + good download speeds. The comparison tool doesn't show any extras.
Any advice on international calls and broadband and telephone would be really helpful, I need to convince him there is cheaper out there.:j