Grandstream HT813 1-Port FXS and 1-Port FXO ATA

The Grandstream HT813 is the ATA with a line in as well as a line out: one FXS port and one FXO port. That combination is what makes it different from every other small adaptor, and it is bought for one reason more than any other — keeping a working phone when the internet is down.

The FXO port takes a real analogue exchange line. Calls can be routed out over it when the SIP trunk is unreachable, and an analogue handset on the FXS port can still reach it. For a site where losing the phones is not acceptable — a surgery, a small hotel, a business with an emergency number — that is worth more than any feature on the spec sheet.

The same port also lets you bring an existing analogue line into a VoIP system, which is the other common reason people buy it: keep the old number without porting it yet.

Key features

• 1 FXS port — for an analogue phone, fax or door phone
• 1 FXO port — for a real analogue exchange line
• PSTN fallback — calls can use the analogue line when SIP is unavailable
• 2 SIP profiles
• Gigabit networking with a built-in NAT router
• T.38 fax relay to 14.4 kbps, with automatic fallback to G.711
• Wide codec support — G.711, G.723.1, G.726, G.729A/B, iLBC and Opus
• TLS and SRTP — signalling and media encryption
• Automated provisioning

Works with

• HT812 V2 — two FXS ports, no analogue line in
• HT814 V2 — four FXS ports
• HT818 — eight FXS ports
• PSU for HT812 / HT813 — spare or replacement power supply
• Grandstream UCM IP PBX range — a UCM has its own FXO ports if you need several

Frequently asked questions

What is the difference between FXS and FXO?

FXS gives a line out — plug an analogue phone or fax into it. FXO takes a line in — plug an analogue exchange line into it. The HT813 has one of each, which is why it can do things a plain ATA cannot.

Will the phone really work if the internet goes down?

If the FXO port has a live analogue line in it, yes — that is the point of the design. It depends entirely on that analogue line still existing, so check it is a real exchange line and not itself delivered over broadband.

Can I keep my old number with this?

You can keep using the line the number is on, which buys you time. It is not a substitute for porting, but it means the migration does not have to happen on one weekend.

HT813 or HT812?

The FXO port. If you only need analogue devices on a SIP system, the HT812 gives you two FXS ports for less. If you need an analogue line coming in — for fallback, or to keep an existing line — only the HT813 does it.

Do I need more than one FXO line?

If you do, a UCM PBX with several FXO ports is usually the better answer than several HT813s.

Planning for an outage, or keeping a line? Call 0333 242 1314 or email sales@clisecure.com and describe the site.