Cell phones and noise

I think everybody has experience sudden cellphone frequencies interfering with their audio equipment at time when cellphone is connecting to the cell towers.   The interence is obvious at those times, but when there is no surge of radio signal communicating, does the music play on the get affected.  How does the SNR drop when no noticible interference is there?  Is it no different than a regular mp3 player at those times?  Can someone explain all this to me?  If noise is not the case, I was considering getting a Samsung, since I'm very satisfied with the P3 and hoping pm3 players on their phones are of the same quality.  Let me know what the downfall of that, I really want a technical explaination.  Thank you.

Come to think about it, the signal is probably being picked up at the cable.  I know for a fact that from my EE wireless com class that the purpose of twisting cable is to remove outside noise of the cable, such as a power cable.  Looks like that became a trend here for line interconnects somehow.  Also, something that is interesting is sony player uses the headphone cable to pick up FM frequencies.  So, I will point to headphone cables to pick up noise.  I guess depends on power being transmitted, like such instances where some data is being pulled from cloud on a smartphone, you get the buzzing or RFI.  Just a thought.  So, even for mp3 player, you get noise.  I need to know for example, iphone 4 versus touch when it comes to typical use SNR, not during the time when data is being clouded or etc...