Automatically switching over to 4G mobile broadband when your home line is down, Telstra's Frontier Gateway aims to ensure that the internet is always there when you need it.

No consumer-grade broadband service can honestly promise that you'll never have an outage, but some services are certainly less reliable than others. Not only are you at the mercy of your Internet Service Provider, you're also at the mercy of the quality of the line running to your door.

Fallback position

Telstra's Frontier Gateway aims to save the day thanks to an onboard 4G SIM card which allows it to automatically switch across to Telstra's mobile network if your fixed line Telstra connection drops out. You're not charged for the mobile data, although one understandable limitation is that Telstra will only sell the Frontier Gateway to you if your home lies within Telstra's 4G mobile footprint.

Unfortunately you don't get the benefit of maximum 4G LTE speeds, the fallback mobile service is capped at around 6 Mbps down and 2 Mbps up. There are two external 4G antenna connectors to assist if you struggle to get a strong mobile broadband signal.

A 6 Mbps link is quite a performance drop if you typically enjoy a home 100 Mbps connection, but it's certainly better than nothing in an emergency. It might actually be faster than your fixed line connection if you're stuck on flaky DSL a long way from the nearest telephone exchange. It could also save the day if you've moved into a new home or ordered a new service and you're stuck waiting for fixed line broadband.

New customers pay $9 per month for the Frontier Gateway on eligible 24-month Telstra plans ($16 for existing customers), or else $219 outright ($384 for existing customers). Put to the test it certainly delivers on its promises, with the 4G backup kicking in within 30 seconds of pulling the plug on your fixed line broadband.

It's not a seamless transition – downloads, streams and VoIP calls are disrupted – but it's enough to ensure you can keep working. When your fixed line service reconnects you'll automatically switch back with 30 seconds. You also receive a text message from Telstra when the fixed line drops out and is restored.

If you're seriously concerned about home broadband outages then the Frontier Gateway might seem like money well spent, but even if downtime isn't a big deal in your home the gateway has a few other tricks up its sleeve.

One handy aspect is that the gateway is designed to work with any Telstra fixed line broadband service. It has a built-in DSL modem, but if you're on Telstra cable then Telstra also supplies a Netgear CM450 DOCSIS3.0 cable modem to sit between the gateway and the wall socket.

The Frontier Gateway will still serve you well when the NBN reaches your home, assuming you're happy to stick with Telstra as your ISP. When the NBN arrives on your doorstep, regardless of how it reaches you, you simply connect the Ethernet port on your NBN NTD box to the WAN port on the Frontier Gateway, allowing the Frontier Gateway to continue to act as the heart of your home network.

Wireless wonderland

Along with an Ethernet WAN port for connecting to your broadband modem, the Gateway features four Ethernet Gigabit LAN ports for connecting to wired devices around your home. It also offers 802.11ac WiFi, supporting 2.4GHz and 5GHz 4x4 MIMO Wi-Fi with directional beamforming and band steering.

In other words it's designed to offer the best possible WiFi speeds to all your devices, old and new, while using multiple antennas to reduce traffic jams on your wireless network. It offers a strong signal which should serve you well in large homes, with band steering enabled by default. With it enabled you can't allocate a different name for the 5GHz network, as the Gateway automatically shifts devices between the 2.4GHz and 5Ghz networks to offer the best service. It can also use beamforming to focus the signal on specific devices.

The Frontier Gateway is also compatible with Telstra Air, offering the option of running a separate isolated WiFi network to act as part of Telstra's nationwide network of public hotspots. In return you gain free access to the Telstra Air network when you're away from home.

Hold the phone

On the front of the Gateway you'll find a USB3.0 port for connecting a printer or external storage, while alongside the Ethernet ports sit four telephone jacks. The first is a line-in for running ADSL/VDSL broadband over your copper telephone line, while the second is a line-in for connecting your PSTN home phone line. The final two are for Voice over IP services – at least in theory.

Once you switch to the NBN, most telcos convert your home phone into a VoIP service – requiring you to plug your telephone handsets into the first VoIP port your gateway rather than the old wall socket. There's no UNI-V voice port on the Frontier Gateway for homes on fibre to the premises which want a more reliable voice service.

In theory you should be able to use the Frontier Gateway with any third-party VoIP provider but frustratingly Telstra locks this down so you can't enter third-party SIP login details. At the same time, like most telcos, Telstra programs the login details for its NBN VoIP home phone service into the gateway and refuses to share them with customers.

This means you're stuck with Telstra's gateway if you want to keep using your NBN-issued VoIP home phone service. If you want to replace the Frontier Gateway with your own VoIP-enabled gateway, like a FritzBox 7490, then you lose the NBN VoIP home phone service as well as the 4G fallback features (the same if you put the Frontier Gateway into Bridge mode).

These various limitations won't bother most people, but if you're a VoIP user it's best to understand this upfront. Keep in mind that the NBN VoIP home phone service and Telstra Air won't work when the Frontier Gateway is running over 4G. As an aside, you do have the freedom to edit the Frontier Gateway's DNS settings, unlike some Telstra-issued gateways.

Like the FritzBox 7490, the Frontier Gateway can also act as a DECT base station for your cordless home phones such as Telstra's T-Voice 502 or 503, although your mileage may vary if you opt for a different brand of DECT handset. Unfortunately the Frontier Gateway doesn't share the FritzBox 7490's ability to act as an answering machine and email you your messages, instead Telstra assumes that you'll use MessageBank or plug in an old fashioned answering machine.

So what's the verdict?

Some of us are satisfied to generate a WiFi hotspot with our smartphone when our home internet is down, but if 4G fallback would regularly save the day in your home then the Telstra Frontier Gateway has a lot going for it. Especially as that mobile data doesn't cost you extra as it comes from your home broadband allowance.

The Frontier Gateway is also attractive if you want a more advanced gateway than Telstra's basic offerings, without opting for a third-party gateway like a FritzBox 7490 and losing the ability to access your NBN VoIP home phone service. In return the Frontier Gateway sacrifices some features and flexibility compared to its rivals, so consider your needs carefully before taking the plunge.