Although most of our customers use our termination with smartphones and ATAs, some use it with Private Branch eXchanges (PBXs). PBX telephone systems support incoming calls from the outside copper-wire traditional phone system (PSTN), placing calls between users' phones (also known as extensions) and other phones or the outside PSTN, conferencing other users together, recording voicemails, and a variety of other advanced telecommunications functions. PBX systems are broadly divided into several categories: traditional (also known as legacy); converged (also known as hybrid) or pure IP, aka IP-PBX.

• Traditional PBX systems usually either don't support IP at all or they support it only with expensive add-on equipment.
• Converged PBX systems support IP and PSTN connections equally. It is the most flexible and cost-effective model.
• IP-PBX systems — as the name implies —support only IP connectivity. Any PSTN connectivity must be achieved through external converters, known as Gateways.

The samples below should be sufficient to set up most PBXs in use today.