What is the ruling on buying a mobile phone that contains musical sounds that cannot be deleted, if there is no alternative free from these forbidden things?

Using musical tones as mobile phone alerts is objectionable. One can use the usual bell tone or a permissible sound like the gurgling of water, birds chirping, or a permissible anthem. As for merely purchasing a phone that includes forbidden musical sounds, there is no harm in it, so long as the owner will not use them.