What sort of phone have you bought , a corded one or cordless , when you say it doesn’t work , what’s the exact problem, no dialtone , or dialtone remains after the number has been ‘dialed’ , or you get announcements like ‘ the number you have dialed has not been recognised’
TBH, there is no adapter needed , that’s just for broadband users that can’t plug their phone directly into the broadband router (so as you don’t have broadband it’s irrelevant)
Your new corded or cordless phone plugged into the master socket in the same way as the old phone when the old phone works , and the new one doesn’t (assuming it’s no dialtone at all , rather than unable to break dialtone ) suggests it’s simply broken, even new stuff can be faulty, no adapter can fix that .
If you get dialtone , check the signaling settings, LD (loop disconnect, that’s pulses representing the number pressed , DTMF , that’s the tones you hear when pressing the number on a modern phone , normally it needs to be set to MF unless your current phone uses pulses , so if one setting doesn’t work try the other , but this is only if you get dialtone on the new phone …
