4G 'light' pipe wanted - how to get 4G inside?

[readiescards]

Our barn conversion to holiday cottage coming on nicely.  We've use foil backed insulation in roof, triple glazed the windows and the walls are 3 bricks solid with an internal plasterboarded shell.  All nice and cosy but the GSM phone signal can't get in!  4 bars of 4G outside but no signal inside.

 

If I was living there then I'd get a Vodafone Suresignal thingy - plugs into the router and acts as a mini 4G cell.  But as we will have guests using many different mobile phone providers I could do with a multi mobile provider solution.

 

Is there such a thing as a light pipe for radio signals?

[ProDave]

You can buy repeaters on ebay, of dubious legality but they do work.

[Tennentslager]

https://m.ebay.co.uk/itm/GSM-900MHz-LCD-Mobile-Cell-Phone-2G-Signal-Booster-Amplifier-EU-Plug/292592241021?hash=item441fdb497d:g:A2oAAOSwwq1axJw7

If you do make sure it's the correct frequency...look at the item description in this link for a list of UK providers and the frequency they use.