Phone doesn't ring on incoming calls, landline or mobile.If 'click' heard, can pick up and speak to caller.?

Followed Bt's fault finder, fig 2, tried 3 other tested phones in same socket - & test socket, none ring. Wires all connected. Dialling tone OK. Normal ringing tones by person contacting. If phone clicks can pick up and reply in normal way. Can make calls out, no problem. Only 1 phone on line. Any ideas how to correct, please?