Complex sentence: The original name of QQ was OICQ ("Open ICQ "), based on a previous instant messaging service (IMS), ICQ, the abbreviation of which came from using letters that sounded like"I seek you".
Split into simpler sentences: The original name of QQ was OICQ ("Open ICQ "), based on an extant instant messaging service (IMS), ICQ. The abbreviation"ICQ " came from using letters that sound like"I seek you".