The simplest method of getting a California area code is to buy a new phone and establish service within the state. It may also be possible to request a new area code from an existing service provider from outside the state.
Service providers may allow existing customers to change area codes upon request. Since this involves receiving a new number, however, there may be a fee.
An alternative for businesses is to subscribe to an answering service in California that can forward phone calls to an out-of-state number. These services can either automatically forward calls or have calls answered by an operator who can screen calls and take messages.