Final answer:
The device that terminates the DSL signal coming from a customer is a modem, which converts the analog signal into digital format for computer use.
Step-by-step explanation:
The device that terminates the DSL signal coming from a customer is a modem. The modem's role is to convert the analog signal received via the telephone line into a digital signal that can be understood and processed by the customer's computer or router. On the other side of the connection, a DSLAM (Digital Subscriber Line Access Multiplexer) is used by the Internet Service Provider to aggregate multiple customer DSL connections and connect them to the larger internet network.