Flat rate internatioal call plan deals?

buglawton

We make 3-4 hours of international calls per week including Asia (10% are mobile).

Had some spam from BT business about a £15 per month eat as much as you like plan, unlimited calls anywhere. Several catches, e.g. is really £22.50 not £15 unless you take their broadband, since we are on a real cable street, no thanks. But the biggest small print catch is the £500 per year minimum spend with BT condition.

So: are there any other good flat rate plans out there? (forget VOIP we tried them all and the quality to Asia is not reliable enough).