Any "unlimited" service suitable for callback?

[RTuesday]

Originally Posted by prion

Which city in Mexico?

Mexicali area code (+52 686). I know there are some tariffs which are limited to Mexico City, or perhaps the big three cities. But this would need to be a tariff that covers landlines in more/most of the country.

Looking around it seems like I can get the call cost below 4c/min (Mexico landline to US/UK) with callwithus.com callback, which is more than cheap enough for a low user like me. Would be nice to find something flat-rate for those who need it.