Grandstream UCM6302A Audio Series IP PBX

The Grandstream UCM6302A is an on-premise IP PBX for up to 500 SIP users and 75 concurrent calls, with two FXS ports, two FXO ports, three Gigabit network ports with PoE, and five audio conference rooms holding up to 75 parties.

The A means audio only — and for most businesses that is the right choice. The non-A UCM6302 adds video meeting hosting. Almost every organisation already runs video on Teams, Zoom or Meet, and duplicating it inside the phone system is money spent on a feature nobody migrates to. Buy the A unless you specifically want video hosted on the PBX.

The two FXO and two FXS ports are what make this the practical mid-range choice. Two FXO ports connect two real telephone lines — useful as a fallback when the internet fails, and often required for a lift line or an alarm. Two FXS ports keep an analogue handset or a fax working. That covers what most sites actually have left over from the analogue era without buying a separate gateway.

Key features

• Up to 500 SIP users — extensions registered to the system
• 75 concurrent calls — the figure that actually sizes the platform
• 75 SRTP encrypted calls — encryption without a capacity penalty
• 2 FXO ports — connect two analogue telephone lines
• 2 FXS ports with lifeline — keep an analogue phone or fax, with dial tone in a failure
• 5 audio conference rooms, up to 75 parties — meetings on your own system
• 3 Gigabit network ports with PoE — WAN, LAN and a powered port
• USB and SD card interfaces — local storage for recordings and backups
• Call recording, IVR, queues and voicemail — the full business feature set

Works with

• Grandstream UCM6300A — 250 users, no analogue ports
• Grandstream UCM6304A — 1,000 users and 4 FXS / 4 FXO ports
• Grandstream UCM6308A — 1,500 users and 8 FXS / 8 FXO ports
• Grandstream GRP2603P — a desk phone to register to it
• Grandstream DP752 — DECT cordless on the same platform
• PSU for UCM620x — spare or replacement adapter
• All IP PBX solutions

Frequently asked questions

What does the A actually change?

It removes video meeting hosting. Voice, messaging, audio conferencing, recording, queues and IVR are all still there. If your video already happens on Teams or Zoom, you lose nothing and pay less.

500 users or 75 calls — which is the real limit?

The 75 concurrent calls. Users are just registrations; what sizes a PBX is how many people talk at once. A normal office rarely exceeds one call per four or five staff at peak.

What are the FXO ports for?

Connecting real analogue telephone lines — typically kept as a fallback for when the internet is down, or because a lift line or alarm line legally has to stay.

What does lifeline on the FXS ports mean?

If power or the network fails, a phone on the FXS port falls through to an analogue line and still gets dial tone. That is the reason those ports are specified in care homes and buildings with lifts.

Do I need a licence?

The PBX features are on the box. UCM RemoteConnect, for remote workers and remote management, is a separate subscription — tell us if that is part of the plan.

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 far cheaper to design in than to retrofit.

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