As BatBoy says, or simply add a cheap Wireless Access Point. (If you have an old working wireless router such as the O2 one that can also be set up to increase wireless coverage).
I also suggest re your line and call costs that you look at Pulse8Broadband
, which is where I moved my line to from BT. Rental £13pm including basic 1571, plus I pay £1pm for Caller Display.
(I expect that link opens on the Business tab, so click the Home one).
Calls are 1ppm in peak, 0.8ppm offpeak, billed by the second. No call setup charge.
IIRC BT Anytime package is £7? That's 700 minutes, before you start eating into the rental saving.
Kindness isn't going to cure the world of all its awfulness but it's a good place to begin. Daisy Ridley.
My broadband basic info/help site - www.robertos.me.uk.
Domains, site and mail hosting - Tsohost
Connection - AAISP Home::1 80/20. Sync 59546/15321kbps @ 600m. - BQM