Naturally, voice quality should be a top priority. You can't save money if employees won't use the system. However, business-quality voice over the Internet is still a distant goal. Ask vendors to give you estimates for the specific configuration you need. Be sure to also think about a gateway's life-cycle cost.
Installation can be relatively complex, and ongoing maintenance expenses are significant.
Today, most buyers expect a payback in one year or less. A return on investment is often achievable in just a few months if your company makes lots of international calls. The few products in the chart that support analog lines are designed for small offices that only use a few phone lines. More than half of the gateways also feature automatic public switched telephone network fallback. The very need for such phone network backup highlights the comparative frailty of IP telephony systems.