Broadband BT Home Hub Phones

BT Signal Assist review: is this the answer to poor mobile reception?

BT Signal Assists
On message: BT Signal Assist will avoid mobile dropouts

I live in one of those houses that seems to suffer from poor mobile reception, no matter which network I join. Until now, that’s meant patchy conversations and dropped calls. Wi-Fi Calling helped briefly but then an update to Android ruined that, too. As a last resort before returning to yoghurt pots and string, I ordered a BT Signal Assist device last week. It might just be the answer – but it’s not without its problems.

What is BT Signal Assist?

BT Signal Assist is a femtocell – a device that boosts your home mobile reception.

It does this by plugging into your home broadband router and routing calls over the internet, a bit like Wi-Fi Calling. The key difference being you don’t need to switch on any special features on your phone – it just sees a strong mobile signal and latches onto it, as if you had a mobile phone mast in your back garden.

The BT Signal Assist is roughly the size of a broadband router and uses roughly the same amount of energy.

BT Signal Assist

BT sells the Signal Assists from its online store although it does a pretty fine job of hiding them away. I get the impression they don’t really want customers finding these devices. I had to ask BT for one specifically – the support guy didn’t volunteer one as a solution for my long-running reception problems.

Note that these devices are locked to the network that sells them, so only BT Mobile customers will benefit from a BT Signal Assist (I have a sneaking suspicion users of parent network EE will too, but I don’t have an EE SIM to test that).

However, other mobile networks offers their own femtocells. The model I’m reviewing here is the Cisco USC3331, which may also be used by other mobile networks in the UK and abroad.

The Signal Assist costs a modest £19.99, although BT gave me a £10 discount because of my ongoing signal hassle, so it’s worth a conversation with the support guys before you place an order if you’re in a similar signal-free boat.

How difficult is it to set up a BT Signal Assist?

It’s a piece of Battenberg. You plug the BT Signal Assist into the power socket, run the supplied Ethernet cord from the Signal Assist to your home broadband router and that’s about it. It’s pretty much idiot-proof.

The only annoying bit is that the BT Signal Assist needs to be activated at BT’s end. The box warned that this could take up to three working days, although I got mine on Friday morning and by Saturday lunchtime it was working. You’ll know it’s been activated when the light on the front of the device stops flashing and goes a solid green.

What’s the catch?

The big drawback with the BT Signal Assist is that it only broadcasts a 3G signal, not 4G or even the cutting-edge 5G.

The problem with my mobile reception is the weakness of the 4G signal. That means that, if I didn’t change any settings on my phone, my problems would still persist because the phone would attempt to cling to the weak 4G. (Phones are meant to automatically fall back on 3G if they can’t get 4G, but that doesn’t work reliably in my experience.)

So, I’ve had to change my phone’s network settings to only look for 2G/3G networks and switched off 4G. That’s not a problem in the home, because my phone is connected to Wi-Fi and that’s faster than any mobile data network. But when I’m out and about, I’m limited to 3G unless I remember to adjust the settings.

I’m hoping an app such as Android’s Tasker will switch on 4G automatically when I leave the house, but I’ve not figured out a way to do this yet.

Does BT Signal Assist boost call quality?

Yes, massively. I’ve got a pretty modest semi-detached house (you guys need to click on more ads, buy more of my magazines, mention me in your wills), but the femtocell’s signal is strong in every room in my house and right down the bottom of the garden. I work in a garden office that has two bricks walls between me and the Signal Assist, and I get a near-perfect signal.

My calls have stopped dropping after 30 seconds, I don’t spend half of every call asking if someone’s still there, the call quality is perfect. It’s the best technological tenner I’ve ever spent.

Granted, it’s only been a few days and I’ll update this piece if I suffer long-term reliability issues, but right now I’d heartily recommend one to anyone suffering from iffy reception on BT Mobile.

BT Signal Assist £19.99
  • Ease of use
  • Features
  • Value for money

BT Signal Assist verdict

A great, cheap solution to dropped calls for those who suffer from weak BT Mobile signal



  • A doodle to set up
  • Almost ridiculously cheap
  • Provides a strong signal throughout the home


  • No 4G or 5G support

About the author

Barry Collins

Barry has scribbled about tech for almost 20 years for The Sunday Times, PC Pro, WebUser, Which? and many others. He was once Deputy Editor of Mail Online and remains in therapy to this day. Email Barry at


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  • Where the divil can I buy one of these BT signal assist yokes????
    I’m dizzy going round in circles trying to source one.