Presently our UPS Ground shipping calculator can only perform live rate-lookups for UPS Ground shipping to US-based destinations. You can set up additional Shipping Rules to apply a custom rate calculation for All Countries (rest of world) using flat-rate, price-per-item or price-per-weight methods.
You could even use a USPS Priority Mail rate-lookup calculation and ship by UPS anyway. What service you use to actually ship orders is entirely up to you and need not depend on a live rate calculation for that particular service in the cart.
