i think it is lack of adab to do so specially in front of rawDah mubarak of the beloved prophet a'laihi afDalus salat wat-tasleem. We know that sah'abah used to sit in his presence as if birds were sitting on their heads; therefore, how it would be permissible to do these exra activities. besides, though i should not blame anyone, sometime it may lead to show off while person may not realize it. i have too done it several times but not in front of the blessed fence, often many meters away out side the masjid sharif or beside the wall near to baqi'y sharif. but, still a dear brother, who i called from there, forbade me to do so, and i think he was right.
a brother said a beautiful thing to me recently. when friends or relatives go to the mazar of a wali etc. they will sometimes ring home and say, "I am standing right next to the mazar, present your salam" - and the person will do so. the brother said that people have offered him to do that from madinah sharif at the rawDah Mubarak and he refuses because he says, rasulAllah sallAllahu alayhi wa sallam hears my salam from anywhere in the world! --- ps: I'm not saying it's forbidden etc. to say salam over the phone but just showing the beauty of his fikr.
