I just passed Iran, now I'm in Pakistan. From Mashhad I rode to east near Turkmenistan border, then I headed down to south by the border and when I reach to Afghanistan border the roads were closed by military, then I accidenty got a road which comes too close to Afghan border, then meet the soldiers and spent my 24 hours with the military. I didnt arrested but lost one day for the paperwork.
Every soldier that I met during this 24 hours asked me about my GPS, I have no GPS with me but my mobile phone has, as every smart phone has nowadays. When I asked them that is GPS forbidden in Iran they said yes, I think they don't know the exact restrictions.
But at the border crossings or on the road no police asked me about that if I have GPS.