The cellphone is a great invention, no question about it. Unfortunately, just like many other great inventions, its potential for abuse is great.
One of the darker sides of the cellphone is when it starts ringing when you are in the synagogue. Many synagogues in Israel have a sign at the entrance reminding worshippers to turn off their cellphones before entering. Unfortunately, many people do not heed the warning and the prayers are sometimes marred by the sound of the various cellphone rings/melodies. Here I confess my sins as I too was once guilty of this. My wife had chosen to call me in the middle of Mincha, and the strains of Fur Elise filled the synagogue. I don't think that Beethoven would have been proud.
Since then my cellphone is always set to vibrate, and not to ring. Sometimes I miss calls because I don't fell the "good vibrations". However, this is the price I pay for not having my cellphone "go off" at the "wrong" time.
Why am I writing all this? Recently I was at a funeral. A large crowd with tears in their eyes gathered to pay last respects to the deceased. A rabbi was in the middle of his eulogy. All of a sudden, somebody's cellphone rings with a nice cheery melody! How do you spell inappropriate?
So my advice to all is to keep the cellphone set on vibrating mode, and of course not to waste time on needless conversations.