3CX runs a licence-based setup for all PABX / VOIP phone systems. Without a licence they won't be able to make calls. Like most software, it is a subscription which is renewed annually. The licence is based on the number of simultaneous calls required that routes through the system. The three types of licences are: Standard, Pro and Enterprise. We sell these licenses based on our recommendation to the client and we always provide a quote for them to review and approve prior to purchase. This includes the annual renewal, as we may need to assess whether the type of licenses still suits their (hopefully growing!) business needs.
How To Quote A 3CX License