Grandstream UCM6208 IP PBX

The Grandstream UCM6208 is an on-premise IP PBX for up to 800 users and 100 concurrent calls, with eight FXO ports for analogue lines, two FXS ports for analogue devices, two Gigabit Ethernet ports and support for up to 200 SIP trunk accounts.

The port split is what distinguishes it. Eight FXO and two FXS is a line-heavy layout — it assumes you have a lot of incoming analogue lines to keep and only a couple of analogue devices. That suits an established business mid-migration far better than a balanced port count does, and it is why the UCM6208 stayed in service so long.

Six conference bridges hold 32 attendees each, and the platform handles up to 45 WebRTC sessions alongside its 100 audio calls. SRTP, TLS and HTTPS are supported throughout, with full Layer 2 and Layer 3 QoS so voice can be prioritised properly on a shared network.

Key features

• Up to 800 users — extensions registered to the system
• 100 concurrent calls — the figure that actually sizes the platform
• 8 FXO ports — connect eight analogue telephone lines
• 2 FXS ports — keep an analogue phone or fax working
• Up to 200 SIP trunk accounts — room for several providers
• 6 conference bridges, 32 attendees each — meetings on your own system
• Up to 45 WebRTC sessions — browser-based calling alongside the handsets
• SRTP, TLS and HTTPS — encryption for signalling, media and management
• Layer 2 and Layer 3 QoS — voice prioritised properly on a shared network
• 2 Gigabit Ethernet ports — separate the trunk side from the LAN

Works with

• Grandstream UCM6304A — the current-generation equivalent
• Grandstream UCM6308A — 1,500 users with 8 FXS and 8 FXO
• Grandstream HT881 — add eight more analogue lines separately
• PSU for UCM620x — spare or replacement adapter
• Grandstream GRP2603P — a desk phone to register to it
• All IP PBX solutions

Frequently asked questions

800 users or 100 calls — which is the real limit?

The 100 concurrent calls. Users are just registrations; what sizes a PBX is how many people talk at once. Size against your busiest hour rather than your headcount.

Why eight FXO but only two FXS?

Because it is built for businesses with lots of incoming lines and few analogue devices. If you have it the other way round — many analogue handsets, few lines — an FXS gateway alongside a smaller PBX is a better fit.

Should I buy this or a UCM6300-series model?

For a new installation, the UCM6300 series is the current generation and the safer specification. Buy the UCM6208 to match an existing estate, or where its eight-FXO layout is exactly what the site needs.

Can I run more than one SIP provider?

Yes — up to 200 SIP trunk accounts, which is far more than most businesses use. Running two providers is a common and sensible resilience measure.

What happens if it fails?

An on-premise PBX is a single point of failure unless you plan for it. Ask us about redundancy before you commit — it is much cheaper to design in than to retrofit.

Does it support encrypted calls?

Yes — SRTP for media, TLS for signalling and HTTPS for management.

Sizing a phone system? Call 0333 242 1314 or email sales@clisecure.com with your headcount, busiest-hour call volume and the analogue lines you must keep.