Once, while I was in Grad School, I was told in not so many nice words by my roommate that I shouldn't be eavesdropping on his calls or trying to second guess from whom he received mails based on the handwriting on the envelopes. The only problem was that when he talked even our neighboring grad mates and their neighbors on the other side knew with whom he was talking to. And the mails would come almost everyday cluttering up the mailbox.
So expecting me not to be curious about his business was out of question until and unless I was blind as a bat or deaf as a post. But an advice is an advice. And so I had to take it. From then on, whenever he asked me if he received any calls while he was away or if he had received any mails, I used to feign ignorance. To the extent that his friends began to complain that I never recognized their voices anymore and asked them their names every time despite them calling up at least half-a-dozen times everyday. Similarly, I stopped picking his mail from the mailbox. Not my bad. Definitely not my bad. Unfortunately this move of mine also frustrated my roommate to no end. But then it was no longer my business to take his calls or pick his mails. All things considered, it was a lesson learnt, for both of us.
Nevertheless, I do agree with him with regard to phone calls. Every phone call is personal, and the person talking should be given due privacy. Even if it is a telemarketing call. But when the person is making no attempt to keep the conversation discreet, then he or she should not expect others to ignore it altogether. So unintentional eavesdropping should not be considered as eavesdropping but as a conversation that is being shared with the people around or is meant to be overheard. I've overheard agitated conversations in hospitals which made me scream 'Too much information!' in silence, I've overheard conversations in railway stations that helped me figure out which train to catch, I've overheard conversations at malls that informed me which store was offering the best discount on what items, and I've overheard conversations in office corridors about how much bonus was to be expected this year. I've even overheard juicy conversations in meeting rooms while a very important meeting was going on. But I must mention here that all of these conversations happened to take place in my immediate proximity while I was cornered and without an escape plan. And thus, despite my best attempts, I get sucked into this vortex of overhearing things. But thanks to such incidents, I've learned to be more discreet with my own phone calls and if need be I ask the caller to call back later rather put the other people around me in a state of undisguised embarrassment.
For this, apart from thanking my experience, I should also thank my Grad School roomie for that piece of advice. Loud or not, frustrating or not, he was right.