3CX is an open-platform IP PBX which gives users complete freedom of choice. Choose the IP Phones and SIP Trunks you want to use too from the list of supported hardware and services. With 3CX you can save up to 80% on monthly telco bills. Pricing is not based on the number of users/extensions you have but on the number of simultaneous calls you need, knocking down the cost of ownership tremendously. Installation, management and use of 3CX is extremely easy and straightforward saving you time on PBX management and maintenance. 3CX has 3 editions; Standard, PRO and Enterprise and all come with their set of Unified Communications features such as smartphone and desktop apps, web conferencing, status, chat and so on... All bundled in the initial price so there are no hidden costs and extra add-ons. Choose the edition that suits your business needs. You can even try the Standard edition for free! https://www.3cx.com/phone-system/download-phone-system/