Facebook shows friends personal cell phones online

Yesterday a friend alerted me a privacy concern on Facebook.  It seems that you can view people's cell phones on Facebook.  I think this is a pretty big concern, especially since it needed to be found out.  I will need to find the time to see how to change the privacy settings.  I haven't yet checked out to see if the reason this happens is when people post to Facebook using their cell phones or not.  I don't post often to Facebook but when I do I use my laptop.  I will provide more information when I check out Facebook later today.