With the advent of cellular phone service, the basic structure did not change, but the services use different equipment than that used by the traditional networks, the companies are often different, and everything had to be renegotiated. There are often multiple providers for the originating and the termination portions of the call, since with cellular systems, in which the signal (the call) is transmitted between the customer and the central office via digital radio (before 2008, analog radio) rather than copper wire, the cost of setting up a new or competing service is far lower.