You just need to put your landline base unit under the stairs next to the hub behind the door and buy a satelite charger for your model of phone then you can put the handset anywhere you want. 

Being awkward doesn't allow you to leave contract penalty free

You can unscrew it or look around the flat to find the end of it and use that instead.  It's not going back out to the street

10 is a bizarre frequency to use, it will cause interference, you really should only use 1 6 and 11.https://www.intel.com/content/www/us/en/support/articles/000058989/wireless/intel-killer-wi-fi-products.html#:~:text=On%20the%202.4%20GHz%20band,on%20...