What is the digital network used to create the route a call takes called?

The digital network used to create the route a call takes is referred to as SS7, or Signaling System No. 7. SS7 is a set of telephony signaling protocols that are used to set up and manage the connection of phone calls over public switched telephone networks (PSTNs) as well as facilitate communication between different network components.

The significance of SS7 lies in its ability to manage routing and signaling for call setups and teardowns efficiently while allowing for features like number portability, prepaid billing, and call control functions, which have become integral in modern telecommunications. This system ensures that data regarding the call’s path, billing, and ongoing management is handled properly without introducing delays or additional complexity.

In contrast, the other options—Frame Relay, X.25, and Ethernet—primarily relate to wider data networking protocols and technologies rather than the specific signaling functions of call routing in traditional telecommunications. Frame Relay and X.25 are older WAN technologies that provide packet-switched data communications, while Ethernet predominantly pertains to local area network (LAN) connections and does not focus on telephony signaling. This distinction highlights why SS7 is the appropriate answer, as it specifically deals with the call routing process in telecommunication networks.