This sort of issue requires you to check if the base or the phone line has a problem.
I prefer to use an old corded phone for testing. I also get a new RJ-11 cable. Unplug your phone base from the jack and check for dial tone when you plug in your test phone.
If you get a dial tone on the test phone, try the new cable with your cordless phone. If you still get that message, then the phone has failed. If it is under warranty, contact the manufacturer for repairs. If it is out of warranty, then determine if it is worth fixing or replacing. These phones are not designed to be fixed by the end user.
If you do not have a dial tone, take your test phone to another jack on the phone line. Check if there is a dial tone at that point. If there is a dial tone, the problem is at the first jack or the phone line to the jack.
If you still do not have a dial tone at the second jack, find where your telephone service comes in. Open the box and determine the type of connection used. If you are lucky, it will have RJ-11 connections. Plug your test phone into the jack and check for a dial tone. If you do not have a dial tone at this point, call your telephone company. They will fix the problem for free. If you find that the connection is not an RJ-11 type, call the phone company and have them test the line and repair it if needed.
If you have a dial tone at the service box, then you have an inside wiring problem. Inspect the visible wires for damage. Open the faceplates for the jacks and check for loose wires. There are two types of connectors. Screw type connectors need the wire stripped back a little then wrap around the screw and tighten. The other type is a punchdown jack. To repair a loose wire in this, you will need a punchdown tool. These are often available in hardware/home improvement stores in the wiring section. http://www.lanshack.com/wire_phone_jack.aspx
has clear pictures of the wire color to pin pattern.
You may want a professional to check the wires inside the walls. Your telephone provider will do this for a fee.
I hope this helps.
(who has had outside phone line problems due to rodents chewing on wires, road crews digging just a little too much, and lightning damaging a DSL filter.)