The Changing Concepts of Telephony
Traditional POTS (Plain Old Telephone Service) lines came into existence in 1876 and outside of updating the PSTN (Public Switched Telephone Network) through digitalization and DSL, has not changed much since. Though instrumental to business, the concept of sending and receiving analog voice over a receiver has been not needed to evolve as quickly as say transportation, computation, or logistics to meet the needs of ever expansive business operations. Luckily, personal computing models and programming have intersected with telephony with the increased capabilities of broadband networks, VDSL, and even Wireless transmissions. The result is a change in how businesses can refer to and use modern telephony.
Do Lines Still Exist?
The traditional concept of having a single-user circuit on a telephony system, commonly referred to as a "Line", is so ingrained into business telephony that it may never leave the service provider dialogue. However, there is a key difference between the traditional LINE and a VoIP LINE, namely concurrency. Lines by definition refer to a single users ability to talk over the telephone system with another individual or service (such as Voice Mail). It supposes that this individuals use of the LINE, precludes any other users ability to use that line. SIP Trunks and other VoIP lines do not always have this exception. A SIP Trunk can handle as many concurrent calls as the VoIP provider allows it. The reason for this is that in SIP based telephony, the conversation or transmission of voice data, is commonly handed off by the server to the devices actually being used. As a result, the SIP Trunk is available to handle additional calls or connections.
TIP: Providers may still discuss lines, but don’t assume that every provider believes this to be of limited concurrency. Ask how many concurrent calls are available per line, you may be surprised!

