Whilst VoIP offers the benefits of low or zero capita costs, the overall total cost of ownership is likely to be higher by about Year 4. If you already have a phone system in place upgrading it to SIP may be a cheaper option.
An IP PBX gives you ultimate control of what happens to any call. It really does depend on the complexity of your telephony requirements and the nature of the business.
Equinox will work with you to help you decide whether VoIP or an IP PBX is the best solution for your business.