V.70

ITU V.70 is a standard for Digital Simultaneous Voice and Data (DSVD), a MODEM related standard wherein digitized voice is mixed with digital data over a POTS line or leased line.

DSVD allows users of two DSVD capable modems to simultaneously engage in a point-to-point voice conversation and data transmission. DSVD does not appear to allow dialup internet users or users of point to point modem connections (such as to the office or a BBS system) to make or receive arbitrary voice calls while online in ordinary circumstances though this may theoretically be possible in special circumstances such as when the user's internet service provider and telephone service provider are the same organization and/or with special equipment on the telco end in place of a normal Subscriber Line Interface Circuit (SLIC). Today, such a service, if offered, would typically be provided via VoIP, ISDN, and/or via DSL over the same wires as an analog POTS line. This standard was released in 1996, at a time when consumer access to The Internet was beginning to take off as were Cell Phones. A google search shows little evidence that DSVD was ever widely adopted, let alone extended to provide the features consumers actually needed (arbitrary calls while connected), and was largely obsoleted by the services offered and the changes in usage that accompanied the rise of The Internet. In the internet model, the user's modem does not connect directly to a site where there may be parties the user wishes to have a voice conversation with but instead connects to an intermediate Network Access Point; as such, the small subset of potential phone conversations served by DSVD was further reduced. During the brief reign of dialup Internet, the ability to carry out an arbitrary voice conversation while online would have been useful, but significant expensive infrastructure, further standardization, and cooperation between ISPs and telcos would have been required and solutions would have been obsolete before they were even fully deployed. DSVD offered too little, too late.

DVSD also does not define a standard for carrying voice and data traffic simultaneously over the interface between a computer and a modem, something that could still be useful today over a USB connection to a cell phone modem.

The [http://www.itu.int/rec/T-REC-V.70-199608-I/en V.70 Standard] can be downloaded free of charge in several languages.Standards G.729, H.245, V.8 bis, V.25 bis, V25 ter, V.32 bis, V.75, V.76, and V.80 are incorporated by reference.

ee Also

*V.61 Analog Simultaneous Voice and Data (ASVD)
*ITU-T V-Series Recommendations‎

References

* [http://www.usb.org/developers/devclass_docs/usbcdc11.pdf USB Communications Device Class Specification]
* [http://www.itu.int/rec/T-REC-V.70-199608-I/en V.70 Standard]