Complex sentence: Eventually Zappa and Varèse spoke on the phone, and they discussed the possibility of meeting each other, however, although this meeting never took place, Zappa did receive a letter from Varèse.
Split into simpler sentences: Eventually Zappa and Varèse spoke on the phone, and they discussed the possibility of meeting each other. Although this meeting never took place, Zappa did receive a letter from Varèse.