my stereo in my ford tranit 2005 model is desplayin PHONE?

i have had a problem with my stereo an cannot clear it, it asked for a code which i have put in correct but it now desplays PHONE i cannot find out how to clear it, it does have a nokia hands free system in it but have only just brought the vechile with no instructions on hands free, the stereo is stuck on PHONE so is not working