Originally Posted by
WIRunner
Apps exist, their legality will depend on your jurisdiction. They are not legal in the US.
Caller-ID spoofing is legal in the US unless it is done for a fraudulent purpose. Congress considered a broader ban but it got watered down based on organized opposition to it from several industries. Roamer has an app which will do what you want in the Apple and Google App stores. It also has a callback number which is handy. Line2 can act as a master number if you want. Your problem will be outbound calls not over VOIP will be pricey. TelnaMobile and Piranha Mobile's SIM can spoof your main caller-id. On Telna it is in the web portal. In Piranha you need to make a special inquiry. A Google Project Fi account might pull off what you want as well.