A local Mufti also told us in one of his tafseer classes that Darul Uloom Deoband give a fatwa that it's impermissible to use Quran as a ring tone astaghfirullah. He gave the above reasons and also said when you answer a call you will have to cut the recitation and he said that is also disrespectful. He also mentioned about listening to Quran while driving or doing other things and said the majority of your attention MUST be on the Quran - you cannot have it on as a background (even if you're not talking - you have to be actively listening to it). And he warned against switching the tape/CD or whatever off in the middle of a verse as this is very common.