
FreePBX is a web-based admin interface that sits on top of Asterisk, the open-source PBX engine. The software is free. The commercial side comes via Sangoma — they sell hardware (the PBXact appliance line, which runs FreePBX with commercial support), per-module add-ons for advanced features (call recording with retention, advanced reporting, CRM integrations), and an annual commercial-support contract.
You can run FreePBX entirely free on a £15/month VPS or a Mini PC at the office. You can also pay Sangoma for add-on modules and support and end up with a per-system cost in the £500–1,500/year range. The product flexes across "fully free DIY" to "paid commercial deployment".
Apples-to-apples is hard because the categories differ:
FreePBX's headline cost is dramatically lower if you have in-house Linux capability. The hidden cost is your time. At £400/day for a senior engineer or business owner, two days a quarter spent on PBX administration is £3,200/year — and that's before something breaks at 4pm Friday.
FreePBX is a great product for the right firm. If your firm runs Linux servers anyway, employs engineers who enjoy this kind of work, and has unusual call-routing needs that benefit from raw Asterisk configurability, stay on FreePBX. If you're spending operational time on phones because there's no managed alternative you trust, that's exactly what managed 3CX exists for. Book a free audit — we'll tell you which case yours is in.