A comprehensive call center incorporates Communication resources :- Telephone, Fax, E-mail, Web, VoIP, etc. ACD and other dialing schemes. IVR. Customer database and integrated infrastructure.  Data and Transaction documentation :- Agent desks, Voice Recording System (VRS), Document Managing System (DMS), Mass Storage. The IVR can collect data from the customer by using Automatic Speech Recognition (ASR) technique or by asking the customer to enter information through the dial pad of the phone (DTMF tones). Using this data, the IVR and ACD decide how to route the call into the system.  Also IVR can connect the call to Auto-Attendant with a pre-recorded answer to the customer enquiry and close the call without any human intervention on the company side, connect the call with a 'hold' message telling the customer that currently all agents are busy and the approximate time that their call will be answered. If the company does not want to lose any calls, the customer may be asked to enter his phone number to be called back as soon as possible. The ACD can also connect the call to  the next available best skilled agent or send back calls to the IVR because the agent found, that the required service will best be supplied by IVR. Outbound dialing to a customer or a potential customer by the company agent is both simplified and speeded up by algorithms like predictive dialing, minimizing down time and optimizing call processing times. Customer agents may swap from outbound to inbound calls or back depending on the system traffic. Networked and distributed call centers also exist, where the caller will not notice that his call is not treated in the city of the dialed destination code. Call forwarding costs will be covered by the telephone infrastructure, with the caller not being affected. Identification using the calling phone number enables 'screen' pop-up of customer data at the agent P.C. even before the caller is connected to the agent  the ACD selected.