Abstract: A method of controlling a telephone office serving a call to obtain a call processing capability not available at the office. A data base executes a customer program unique to a customer in response to each call to the customer. The customer program determines from call parameters how to process a particular call and instructs the serving office to perform specific primitive call processing capabilities to process the call. If the serving office is unable to perform a capability required to process the call in accordance with the customed program, the date base selects a second office which should be able to perform the capability. The call is routed from the first office to the second office under control of the data base and the second office performs one or more call processing capabilities under control of the data base. Call processing may be returned to the first office under control of the data base after a capability is performed at the second office. This is referred to as a service assist.