I have a red light flashing on the 3 cordless units of XDECT 8155+2. I can get the light to stay on by following the menu but it reverts to flashing inside a minute. The phone and base both show mail but pressing the message button gives the answer "no message". In addition friends are telling me that they do not get my recorded message and I obviously not aware of this when I am not home. This problem has only occurred since NBN was installed and a new Telstra modem connected. Can you advise where I should go with this??