Do you know your SIP from your ISDN?

Posted by Karen on Nov 20, 2015 12:00:00 AM
In the technology industry, we all love an acronym but do you know your SIP from your ISDN and which is best for your business? According to Wikipedia, Integrated Services for Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network. ISDN is a circuit-switched telephone network system, which also provides access to packet-switched networks, designed to allow digital transmission of voice and data over ordinary telephone copper wires, resulting in potentially better voice quality than an analogue phone can provide. The Session Initiation Protocol (SIP) is a communications protocol for signalling and controlling multimedia communication sessions. The most common applications of SIP are in Internet telephony for voice and video calls, as well as instant messaging all over Internet Protocol (IP) networks. Essentially ISDN is physical and SIP is virtual. In the past, ISDN has been king. Everyone and every business has had a ‘landline’. But as we have seen in our posts in the last few weeks this is rapidly changing.


The challenge with ISDN has always been the ability to add new phone numbers. A connection has to be made with the BT exchange and then trunking boxes installed in your office for the individual lines to come from. These boxes have a limit of the number of lines that it can feed. So to scale up, physical boxes need to be added.

As SIP connections are virtual there is no physical hardware required. However, even though there isn’t the need for an additional box when adding numbers, there can be the need to add bandwidth or increase data connection speeds. Even with this consideration it is a lot quicker to scale with SIP. ISDN relies on BT which has long lead times. With SIP, an increase can be done almost instantaneously. Comms Business has been speaking with business and is seeing that many are turning to SIP. It found that ‘as more and more UK businesses outgrow their telecommunications solutions, they begin to look for an alternative that offers more flexibility, reliability and value for money.’ The real questions is 'does SIP outperform ISDN in all these areas. The editor says the obvious answer is yes. However, as with anything virtual, the service depends on the internet connection available. So if you are looking to make the switch make sure you choose a provider with high reliability and one that understands the demands on the network.
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