An IP PBX can do everything a traditional small business PBX can do and more. It performs the switching and connecting of Voice over IP as well as landline calls.
A conventional PBX requires two networks, one for data and another for voice. An IP PBX system runs on an IP data network, which saves costs and minimizes network management.
With an IP PBX, you can use IP phones, softphones (which don’t require any phone hardware, beyond a computer and a microphone headset), and many offer apps you can use with mobile smart phones.