My mum has an annual travel insurance plan that is underwritten by Zurich. They pay 100% with no pre-auth needed. Just the Dr's note and a detailed receipt is required for the claim once you return to your home country. The conditions of her plan are that she only has 90days coverage and then she has to return to her "home" country for at least 24 hrs to reset the clock before her travel insurance is active again for another 90 days. Rinse and repeat. When she snowbirds with us for 6 months of the year and she choses to not fly back home and back again, we use her first 90 days of her annual plan then buy the World Trips PPO for an additional 90days. The main problem the the World Trips Insurance is that it does not have a Group # so the provider/biller has to call the 1800 # to speak with someone. As a result, quite a few places claim to not accept it because they can't run it through their computer system automatically and they can't be bothered to put any effort into making the call. In cases like this, you pretty much have to threaten to call the underwriting insurance company (United Healthcare/Blue Cross/etc) and to say that the provider is refusing to honor their contract of service. A downside to international travel insurance that the World Trips PPO does not have is that you have to pay for everything upfront and usually at a much higher non-contract rate so make sure you have enough room on your credit card just in case.
This information is helpful. I'm leaning towards getting a plan unwritten in the US with United Healthcare network. Good to know what to do in the event of being told that they can't run the insurance.