How does a SIP Trunk service really compare to ISDN in terms of cost, quality and reliability?
Below are two comparisons between SIP Trunks and ISDN Telephone Lines, showing both installation and ongoing rental charges. The first comparison is an example using 4 channels of ISDN2e with 20 DDI Numbers, typical of a small business user in the 4-12 extension marketplace. The second comparison uses the example of a larger business using 30 channels of ISDN30e with 200 DDI Numbers.
In our experience, call charges between SIP Trunks and ISDN lines are very similar, after all the calls are being carried by the same tier one carriers so will all be subject to the same core costs so for the purposes of our comparison we are only showing the costs of installation and rental. Our comparison is based upon using a business grade SIP Trunk service provider with high quality broadband services to provide near ISDN call quality and reliability, against ISDN lines provided by a competitive service provider ie. not BT.
