Play busy tone and congestion tone as what is actually requested

(cherry picked from commit 9216e5db)

line.c

@@ -353,7 +353,7 @@ int line_signal(int line, const char *signame, const char *data, struct voice_ub
 					res = dect_tone_play(line, get_callid_state(lines[line].pcm_callid[PCM_0]) == CALLID_ESTABLISHED ? PCM_0 : PCM_1, sig->signal, data, ubus_req);
 				}
 			} else {
-				res = voice_line_signal(line, -1, VOICE_SIG_BUSY, atoi(data), NULL);
+				res = voice_line_signal(line, -1, sig->signal, atoi(data), NULL);
 			}
 			break;