Call Forwarding is Performed in the Switch

• Call Forwarding, a popular service offered by many local and mobile telephone companies, is performed in the telephone company switch. When a customer who subscribes to Call Forwarding activates the service, special software programmed on the customer's line card--or on the customer's logical account in mobile switches--redirects incoming calls to a specified number. In many cases, the service sends a courtesy notification of a half telephone ring to the subscriber's line when a call is forwarded as a reminder that the service is active.
  
  

Call Forwarding Uses Another Switch Connection

• When the Call Forwarding service redirects a call, the call is routed through the standard outbound call trunks connected to the switch. In this capacity, the forwarded call is treated much like any other outbound call processed by the switch. If it is long distance, it might pass through a toll center to charge the appropriate customer; if it is local, it is simply routed to another line card in the central office.
  
  

Long Distance Call Forwarding Incurs Charges

• If a customer activates Call Forwarding, he may select any telephone number to receive the forwarded calls. If the selected number is normally considered long distance from the customer, though, all calls forwarded to the number will be charged the customer's normal long distance rate. Because the switch forwards calls out through standard outbound trunks, and because the call is initiated by programming on the customer's line card, the call is treated and billed just like any other call originating from the customer's line.
  
  

Caller ID Data is Also Transfered

• Although the forwarded call is treated much like any other call originating from the line of the customer who forwarded the call, some identifying information is passed through from the original caller. Important information--like the Automatic Number Identification (ANI), time of call and originating telephone company--is passed through the telephone company's signaling system (currently known in the United States as "Signaling System Seven," or SS7). When the call is signaled and set up at the final forwarded destination, this data is passed so that important caller identification data can be passed to the call recipient.