In my experience, almost anything with a speaker or earphone will detect a cellphone operating nearby :-)
Not here, I have lots of ham radio and other stuff with speakers and I wouldn't tolerate it if cell phone noise came through them. But then again I'm in the northern hemisphere, so perhaps things are different here, like with toilet swirl direction?
Its typically only GSM phones that do this, may be why you havn't heard it in NA, we're mostly CDMA where everyone else is GSM.http://electronics.stackexchange.com/questions/32830/why-does-gsm-cause-speakers-to-buzz
Its my understanding that GSM phones have to "ping" the towers every once in a while, so the tower has an idea how many clients it has in range. This ping uses more power than normal, so speakers pick it up even when they don't pick up normal phone use. Whenever I had friends over in my shop, my speakers would buzz about 5 seconds before one of them would get a text message or call. It almost sounded like Morse code, a series of distorted beeps, then a pause, then more beeps.