Family member called us to find line engaged. Speaking to them later via mobile, we were told that we must be busy as it was constantly engaged. Checked landline cable into wall socket. Checked state of phone and handsets are both fully charged. Had a similar problem a wee while back and bought a new phone to discover that it was the line. Obviously can't call 150 to talk to someone. We can't receive or make calls. Apparently no issues in our area, but unable also to use the ZONE check that we are advised to try.