You're right. They do Phase IV trials after approval. Tibotec has the marketing rights to telaprevir outside the USA.
I'm pretty sure they're about to wrap up the trials, as according to most reports, the drug should be available for sale (in the US, anyhow) mid-year.
Wait - actually, don't they do Phase IV studies even after approval? Not sure.
Check with the reference the previous poster gave. I'm pretty sure the trials listed on clinicaltrials.gov also include study locations outside the US.
RBW
Telaprevir is being handled by Tibotec Therapeutics for trials and marketing in all places except the continental United States. You can write to them at:
Tibotec Therapeutics
1125 Trenton-Harbourton Road
Titusville, NJ 08560
USA