Complex sentence: The Nokia 6600 is a mobile phone launched in the second quarter of 2003, costing approximately €600, was Nokia's high-end model of the 6xxx Classic Business Series of mobile phones.
Split into simpler sentences: The Nokia 6600 is a mobile phone launched in Q2 2003, costing approximately €600. It was Nokia's high-end model of the 6xxx Classic Business Series of mobile phones.