Here in Australia, ISDN Data over Voice (DoV) was in fairly common use. Telstra (the major telecom here particularly in those days) charged an untimed flat "local call" rate (a few tens of cents) for an ISDN voice call, and by the minute for an ISDN data call. It didn't take many minutes for a voice call to be vastly cheaper.
At a technical level both types of call are a 64kbps data connection, with just a flag to discriminate between the two. All the major suppliers (Cisco, Nortel, ...) had software options for their ISDN gateways to tell them to set the voice flag when making an outgoing data connection, and to treat voice calls as data calls when they were received.
This was extremely common and Telstra never seemed to do anything about it. Just a funny memory that this article brought to mind.
At a technical level both types of call are a 64kbps data connection, with just a flag to discriminate between the two. All the major suppliers (Cisco, Nortel, ...) had software options for their ISDN gateways to tell them to set the voice flag when making an outgoing data connection, and to treat voice calls as data calls when they were received.
This was extremely common and Telstra never seemed to do anything about it. Just a funny memory that this article brought to mind.