Time was people would have SIP trunks into their business but always in tandem with an ISDN line. This showed an element of distrust in SIP. They liked the idea of the cost savings that VoIP could bring but had heard it was unreliable.
Even here at Timico we did the same. As a service provider our customer service function is mission critical. When we started our SIP ran over bonded ADSL so we had SIP trunks and ISDN. The funny thing was whenever there was a problem it was with the ISDN line. It was the SIP that always came to the rescue.
This might have been a case specific to us. ADSL is known to not be a totally stable product – every line will lose connection and reconnect over a period of weeks and if it is wet weather the number of faults increases. What I am saying is that there will be some circumstances where it is the ADSL and therefore the SIP line that is the unstable one.
Most of the time both ISDN and ADSL are fine.
There are two factors that are turning SIP into people’s primary means of communication and leading them to drop the cost of ISDN altogether.
Firstly is the growing acceptance of SIP - It’s been with us for a long time now. Timico has been going 8 years and we have been using it most of that time.
Then there is the rise of low cost Ethernet connectivity. Ethernet is a far more stable connectivity solution than ADSL, can carry far more data and has seen its costs plummet over the past couple of years. As a result more and more businesses are switching to Ethernet and relegating ADSL or even FTTC to the role of a backup line.
Now they aren’t doing this for cost reasons. In the main their data/internet usage is rocketing so they are having to install bigger and better IP connections to service this. The side effect is that they now have stable and reliable connections that can also be used to carry SIP traffic.
The cost savings that can then be made by ditching ISDN completely are enormous. For example Honda in the UK saved 45% of their phone bill by moving to SIP running over their Ethernet network.
So there you have it. SIP. Finally becoming the communications mode of choice for fixed line minutes.