The Grandstream GAC2500 will allow you to hold and participate in up to 7 way conferencing. The unit is smart, really user friendly and at a great price point. It runs Android 4.4 which gives it power features and includes a web browser, PoE and will very happily run on WiFi. It allows you to record and store conference calls.
This is by far the best unit we've come across for conferencing. It's easy to set up and use. The colour screen allows you to program and use the power of the unit. The sound quality is HD and the unit has a range of up to 12 feet which means that multiple people can talk from the same office with to up to six external people. With it's smart black exterior and gently glowing blue LEDS when in use and it's colour screen this would look great in any boardroom or on any executives desk.