The IP telephony system will almost always be more cost effective than what preceded it, although in this case, the benefit comes from the upfront cost, as opposed to the ongoing savings from the VoIP service. An IP telephony system will typically be an IP PBX for enterprises, while smaller businesses are more likely to use SIP-based handsets that emulate the PBX feature set via software or web-based VoIP solutions. The scale of cost efficiency is usually greater for the telephony system since the investment can be relatively large, and if the system is being purchased, it only occurs upfront. In cases where the system is leased or financed, then the cost efficiencies recur over time.
As such, the nature of these cost efficiencies is different for each element. To further complicate matters, some providers will bundle the telephony system with their VoIP service, and blend both items into a single monthly price. In those scenarios, it will be very difficult to truly say which element is more cost effective.
This was first published in August 2009