Best time to reach OKC is when they first open in the morning. I tried at every time of the day and would get the sorry we have too many callers, please try at a later time, any other time. Usually first thing in the morning I would get through with a 5-10 minute wait and usually got Ron most of the time, to the point that one day I told him "I think your the only one working there, every time I call you answer." They will put you on hold about 3-5 minutes while they look up your file and most likely come back with the standard "It under review". I even received letters from them the same day I spoke with them on the phone and still got the "It's under review" answer, so just expect that. I also checked under the Airman's Information section of the FAA website, but it also never said anything other than "no medical information available", so that doesn't help either unless they actual issue your medical before you receive it. My simulator partner when I was at ExpressJet did have a stint put in before coming there and the FAA approved him, but I'm not sure how long his wait was. Again best of luck, just keep calling every couple of weeks and send in any items they request and hopefully they will approve you as quick as possible.