Grandstream UCM6300A Audio Series IP PBX

The Grandstream UCM6300A is the entry point to the UCM6300 audio series: an on-premise IP PBX for up to 250 SIP users and 50 concurrent calls, with three audio conference rooms holding up to 50 parties between them.

The A means audio only, and for most businesses that is the right choice rather than a compromise. The non-A models add video meetings to the PBX. Almost every organisation already runs video on Teams, Zoom or Meet, and duplicating that inside the phone system is money spent on a feature nobody will move to. Buy the A unless you have a specific reason to host video on the PBX itself.

It has no FXS or FXO ports — that is what the trailing 0 in the model number means. This is a pure IP platform: SIP trunks in, IP phones out. If you need to connect analogue phone lines or keep an analogue handset or fax alive, either step up to the UCM6302A, which has two of each, or add a separate gateway.

Key features

• Up to 250 SIP users — extensions registered to the system
• 50 concurrent calls — the figure that actually sizes the platform
• 50 SRTP encrypted calls — encryption without a capacity penalty
• 3 audio conference rooms, up to 50 parties — meetings hosted on your own system
• No analogue ports — pure IP; see the UCM6302A if you need FXS or FXO
• Instant messaging and web meetings — part of the UCM6300 ecosystem
• Call recording, IVR, queues and voicemail — the full business feature set
• On-premise — your calls, recordings and data stay on your own hardware

Works with

• Grandstream UCM6302A — 500 users and 2 FXS / 2 FXO ports
• Grandstream UCM6304A — 1,000 users and 4 FXS / 4 FXO ports
• Grandstream HT841 — add analogue line connectivity separately
• Grandstream GRP2603P — a desk phone to register to it
• All Grandstream IP phones
• All IP PBX solutions

Frequently asked questions

What does the A actually change?

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

250 users or 50 calls — which is the real limit?

The 50 concurrent calls. Users are just registrations; what breaks a PBX is everybody talking at once. As a rough guide, a normal office rarely exceeds one call for every four or five staff at peak.

Can I connect analogue lines?

Not directly — this model has no FXO ports. Either choose the UCM6302A, which has two, or add an HT841 or HT881 gateway alongside it.

Can I keep an old fax machine?

Not on this model, which has no FXS port either. The UCM6302A upwards do, or an HT814 handles it separately.

Do I need a licence for the features?

The PBX features are on the box. Remote connectivity through UCM RemoteConnect is a separate subscription — tell us if remote workers are part of the plan and we will include it in the quote.

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.

Sizing a phone system? Call 0333 242 1314 or email sales@clisecure.com with your headcount and busiest-hour call volume, and we will size it properly.