Grandstream HT841 Analog FXO Gateways

The Grandstream HT841 is a four-port analogue FXO gateway. It takes real telephone lines — from the exchange or from an old PBX — and presents them to a SIP platform, so a modern IP phone system can make and take calls on lines that were never designed for it.

FXO and FXS are opposites, and getting them the wrong way round is the most common mistake in this category. An FXO port plugs into a line. An FXS port plugs into a phone or fax. If what you want is to keep an old analogue handset or a fax machine working on a VoIP system, you need an FXS device such as the HT814 — not this. If you want to keep four existing phone lines while moving the phones to IP, this is the right box.

It also has one FXS port, so a fax machine or a single analogue phone can live on the same unit, and lifeline support: if the internet or the power fails, a connected phone still reaches the PSTN line directly. On a site where losing dial tone is a real problem — a lift line, a care home, an alarm panel — that is the feature that justifies the whole purchase.

Key features

• 4 FXO ports — connect four analogue telephone lines from the exchange or a PBX
• 1 FXS port — for a fax machine or a single analogue phone
• 3 SIP profiles — register to more than one platform or provider
• Lifeline support — PSTN calls keep working through a power or internet failure
• Failover SIP server — a second server takes over if the primary is unreachable
• T.38 fax over IP — the protocol that makes fax survive an IP network
• Built-in NAT router — two Ethernet ports, so it can sit inline if needed
• Encryption and secure automated provisioning — deployable at volume

Works with

• Grandstream HT881 — the same gateway with eight FXO ports
• Grandstream GXW4104 — the earlier four-port FXO gateway this replaces
• Grandstream HT814 — the FXS equivalent, for connecting analogue phones and faxes
• Grandstream HT813 — one FXS and one FXO in a single small unit
• Grandstream UCM6302 IP PBX — the platform to register it to
• All Grandstream gateways

Frequently asked questions

FXO or FXS — which do I need?

FXO connects to a line; FXS connects to a phone or fax. Keeping existing telephone lines on a new IP system needs FXO, which is this. Keeping an old handset or fax working needs FXS, which is the HT814 or HT818.

What does lifeline support actually do?

It falls back to a direct connection between the FXS port and a PSTN line when power or internet fails, so a phone plugged into it still gets dial tone. It is the reason FXO gateways are still specified in care homes, lifts and alarm installations.

Will fax work through it?

It supports T.38 fax over IP, which is what makes fax survive an IP network rather than failing halfway through a page. Fax remains fussy — test with the actual machine before you commit.

How is it different from the GXW4104?

The HT841 replaces it with a richer feature set. Same four-port FXO idea; more SIP profiles, better provisioning and current firmware support.

Can it register to two providers at once?

Yes — it supports three SIP profiles, and a failover SIP server if the primary becomes unreachable.

Do I need one port per simultaneous call?

Yes. Each FXO port carries one call at a time, so four ports means four concurrent PSTN calls. Count the busiest hour, not the number of lines you own.

Migrating from analogue lines to SIP? Call 0333 242 1314 or email sales@clisecure.com and we will work out how many ports you actually need.