Abstract: An Internet/telephone adaptor device to link a regular telephone call with an Internet call without requiring software that is specific to each proprietary encoding scheme. The device is designed to operate with a data network terminal haling audio/data conversion means for reversibly converting voice signals to a data format for telephone-like communication over a data network. In a preferred embodiment, the adaptor device is provided as an add-on accessory to existing computer terminals having a sound card, making them capable of handling Internet calls. The adaptor is connected both to the computer and to the telephone line, enabling linkage of regular and Internet calls. With the adaptor device, a user can easily arrange conference calls between Internet users and telephone line users. A hold call feature is also provided to simplify user handling of calls.