All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Songs and music are among the forbidden matters so it is not permissible to download them neither to a mobile phone nor to any other device and you should delete them all in any case. For more benefit on the evidence on the prohibition of songs, please refer to Fataawa 81545 and 81239.
As regards downloading the Quran and songs to the same memory card of a mobile phone or any other device, then one should not do so, and such an act could be a means for degrading the Quran whereas one should honor and glorify it. Allaah Says (what means): {That [is so]. And whoever honors the Symbols of Allaah - indeed, it is from the piety of hearts.}[Quran 22:32] Allaah also Says (what means): {That [has been commanded], and whoever honors the sacred ordinances of Allaah — it is best for him in the sight of his Lord.}[Quran 22:30]
Therefore, you should be careful and be keen on doing what pleases Allaah and avoid what incurs His Wrath.
Finally, it should be mentioned that loving songs and music may repel in one’s heart the love of the Quran as they cannot coexist in the heart of the believer: the Quran is the words of the Most Merciful [i.e. Allaah] and songs and music are the flute of the devil.
May Allaah enable us to do acts of obedience to Him and protect us from acts of disobedience to Him, as He is the All-Hearer and He answers the supplication.
Allaah Knows best.