If you run an ISP or WISP, you've almost certainly heard of SAS4 (also known as SAS Radius). It's a long-standing RADIUS billing system that a lot of networks grew up on. But "long-standing" cuts both ways — a dated stack, per-install licensing and an aging interface. Here's an honest look at how ISP Boost compares, and why so many operators are switching.
What is SAS4 / SAS Radius?
SAS Radius is a PHP-based RADIUS billing and management application used by ISPs to authenticate subscribers, apply data plans, and handle prepaid/postpaid billing on top of MikroTik and other NAS devices. It does the core job well and has a large installed base — which is exactly why we built a one-click importer for it. The friction shows up elsewhere: the UI feels dated, every server needs a paid license, and the business tooling around billing (CRM, helpdesk, inventory, HR) simply isn't there.
Feature & price comparison
| ISP Boost | SAS4 / SAS Radius | |
|---|---|---|
| Starting price | Free · 50 users | Paid license |
| Hosting | Self-hosted (cloud or on-prem) | Self-hosted |
| RADIUS engine | FreeRADIUS 3.2 | FreeRADIUS |
| UI / stack | Modern Angular SPA | Legacy PHP UI |
| MikroTik + any NAS | ✓ | ✓ |
| Resellers / managers | ✓ multi-level, scoped | ✓ |
| Helpdesk & tickets | ✓ built-in | ✗ |
| Inventory · HR · Assets | ✓ built-in | ✗ |
| One-click SAS4 import | ✓ tested on 294K users | — |
| Auto-updates | ✓ verified & safe | Manual |
Comparison compiled May 2026 from public information; competitor capabilities change — always verify current specs.
The stack: modern vs legacy
ISP Boost runs a production FreeRADIUS 3.2 engine — the same battle-tested core — but pairs it with a modern Angular single-page panel on PHP 8.4 + MySQL 8.4. That means fast, responsive screens, a clean mobile layout, dark mode, and a UI your staff can actually learn in an afternoon. Legacy PHP panels get the job done, but every extra minute your team spends fighting the interface is money.
One license per server, no per-user fees. ISP Boost is free for 50 users and paid plans are one flat license per server — not a tax that grows with every subscriber you add.
Billing is only half the job
Running an ISP isn't just AAA and invoices. It's support tickets, staff, stock, reseller balances and reports. With SAS-style tools you bolt those on with spreadsheets and third-party apps. ISP Boost ships them in one panel: a customer CRM, billing & invoicing, multi-level resellers, cards & vouchers, helpdesk, inventory, HR, assets, alerts and analytics. One login, one source of truth, one thing to back up.
Switching without downtime
The scary part of leaving any billing system is the data. We built the importer specifically for SAS4 and tested it on a real 294,000-subscriber database — it brings across subscribers, profiles/packages, managers and balances, so your customers stay online through the switch. There's a full walkthrough in our SAS4 migration guide.
The verdict
If SAS4 / SAS Radius works and you never touch it, there's no emergency. But if you're paying per install, wrestling a dated UI, or duct-taping billing to your CRM and helpdesk, ISP Boost gives you a modern, free-to-start, all-in-one platform on the same reliable FreeRADIUS core — and a one-click path to get there. See the full 2026 platform comparison or just try it.
