Legacy access hardware: what is the name of the modem device that connects to the telephone system by pressing the telephone handset into two rubber cups on the unit?

Introduction / Context:
Before direct-connect modems became common, early data communication often used a device that converted digital signals to audible tones and sent them through a phone handset physically pressed into the unit. Knowing this historical device helps understand the evolution of modem technology and telecommunication interfaces.

Given Data / Assumptions:

• The phone’s handset is inserted into flexible receptacles (“rubber cups”).
• The device converts digital data to audio frequencies and vice versa.
• Used with plain old telephone service handsets in the pre-RJ11 era or in restricted environments.

Concept / Approach:
Such a device is an acoustic coupler. It transmits and receives tones through the handset’s microphone and earpiece, avoiding a direct electrical connection to the phone network. Gateways, bridges, and multiplexers perform network routing/segmenting/aggregation roles and do not match this description.

Step-by-Step Solution:

Verification / Alternative check:
Museum references and early computing texts depict acoustic couplers (e.g., 300 bps) where the handset is clamped into rubber mounts to exchange audio tones.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing any modem with this specific handset-coupled design; modern modems use direct line interfaces, not acoustic coupling.

Final Answer:
acoustic coupler.