Telephone communication for giving (gsm gateway)?

Question

Telephony

Good evening. There is a task - to set up a telephone connection in the village, the main problem is that the connection is reliably caught only on the second floor of the house. Plus, I would like to have a pair of radio tubes to walk around the site with them. The ideal solution, as I understand it, would be to install a gsm gateway (analogue?) on the second floor and connect 2 handsets to it (is this possible?).
Advise which gateway to choose?