The arrival of Ethernet networks in the 1980s meant an increase in demand from businesses with multiple sites to have digital links between them. Of course, this was strictly for data – no one had yet thought of VoIP – but it led to the introduction of frame-relay transport services. These package up data for sending to another site and it’s this that paved the way for IP-based voice services to become practical.
In many cases, ISDN lines brazil telegram were still being used for these links and it’s possible to dedicate channels to different uses, so data and voice could be kept separate to preempt any clash in bandwidth requirements.
Optical services
In more recent times the trend has been to move to fibre optic connections. These can be used for both data and voice and have dramatically increased the bandwidth and the speeds available. This has gone hand-in-hand with the development of the ATM (asynchronous transfer mode) transport service. [1] This became pretty much standard for all communications providers during the 1990s.
However, as Ethernet speeds have increased, the need for ATM has rather been superseded. VoIP and data can now be used over the same fibre optic Ethernet connection, thus simplifying the communication requirements and removing the need for a separate dedicated circuit to handle voice traffic. Bandwidth can be controlled using QoS (Quality of Service) tools to ensure that there is no loss in the quality of voice traffic.
Many company networks still rely on ATM, however, and these are perfectly capable of supporting VoIP traffic so there’s no need for a major reinvestment in network infrastructure.