Contemporary Iranian Persian is described as having a six vowel system; however, there is currently very little work that characterizes the exact nature of these vowels. Previous works posit substantially different vowel spaces, and conflicting accounts of the extent to which historical length distinctions are still relevant in Persian -- these distinctions then affect phonological theorizing, especially with regards to vocalic assimilation (sometimes referred to as "vowel harmony"). This study uses a corpus of over 60 hours of casual telephone speech among 104 speakers to describe the vowels of Persian. It is demonstrated that historical length distinctions no longer obtain, that previous descriptions of the vowel space of Persian are no longer necessarily accurate, and that the low back vowel may no longer be a steady state vowel for all speakers nor as low or as rounded as previously described.