1. Call centers are large office spaces that house many operators who take and respond to customer requests for help using computer systems connected to telephone networks. 2. Computer telephony integration (CTI) software integrates all aspects of the call center system, allowing computer systems to direct calls to operators with the appropriate expertise to handle customer issues. 3. CTI works in either first party control, where an operator's computer directly controls their phone, or third party control, where a dedicated server connects all phone and computer networks and can control any phone.