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The V.61 Standard introduced Analog Simultaneous Voice and Data (ASVD). This technology allowed user's of v.61 modems to engage in point-to-point voice conversations with each other while their respective modems communicated.

In 1995, the first DSVD (Digital Simultaneous Voice and Data) modems became available to consumers, and the standard was ratified as v.70 by the International Telecommunication Union (ITU) in 1996.

Two DSVD modems can establish a completely digital link between each other over standard phone lines. Sometimes referred to as "the poor man's ISDN," and employing a similar technology, v.70 compatible modems allow for a maximum speed of 33.6 kbps between peers. By using a majority of the bandwidth for data and reserving part for voice transmission, DSVD modems allow users to pick up a telephone handset interfaced with the modem, and initiate a call to the other peer.

One practical use for this technology was realized by early two player video gamers, who could hold voice communication with each other while in game over the PSTN.

Advocates of DSVD envisioned whiteboard sharing and other practical applications for the standard, however, with advent of cheaper 56kbps analog modems intended for internet connectivity, peer-to-peer data transmission over the PSTN became quickly irrelevant. Also, the standard was never expanded to allow for the making or receiving of arbitrary phone calls while the modem was in use, due to the cost of infrastructure upgrades to telcos, and the advent of ISDN and DSL technologies which effectively accomplished the same goal.

Today, Multi-Tech is the only known company to continue to support a v.70 compatible modem. While their device also offers v.92 at 56kbps, it remains significantly more expensive than comparable modems sans v.70 support.

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