I've inherited a project that contains one mobile ASPX page. It's completely accessible from a non-mobile device, but 99% of the time it gives 404 (SP's 404: Resource not found "/") from a smartphone.
I have seen this page on a smart phone but it usually takes about 30 refreshes to access it (I'm making that number up...it's seemingly random). My co-worker who has a different carrier has never seen it load. I've tried "site/m/page.aspx", "site/page.aspx", and adding Mobile=1 in the query string with no consistent results.