Usually this means that the phone isn't detecting a dial tone. For diagnostic purposes, I like an old corded phone.
First try a new telephone cable between the jack and the phone. Then try the old phone and see if you have a dial tone. If you have a dial tone with the old phone but not the cordless, then the Uniden needs service. These phones are not designed to be fixed by the user. If the phone is under warranty, send it in. (see page 28 of the manual www.uniden.com/pdf/DECT1480-3om.pdf
If neither phone gets a dial tone, check at another jack if you have several to see if the jack is the problem or if it is a more global problem. If the problem is at one jack, you may want to open the jack and check for a loose wire. Some wall plates hold the wires with screws; others use a keystone jack with the wires pressed into slots using a "punch down tool". Keystone jacks do not need the insulator removed from the individual wires. For the screw connectors, you do need strip the individual wires. The punch down tool is available at many hardware stores in the electrical section (for wiring homes for ethernet and other services).
If you do not have a dial tone at another jack, find where your telephone service comes into your home. Open the panel and identify how the connection is set up. Some use RJ-11 jacks. In that case, plug in your test phone and see if there is a dial tone at that point. If there is no dial tone, contact your phone company for service. There is a break in the wires coming into your home. The phone company will fix this for free. (If the service doesn't use an RJ-11 jack, you need a special adapter to test at this point. Your phone company technicians will have this.)
If there is a dial tone at the incoming service, you have a inside wiring problem. Check any visible phone wiring for damage to the insulation. If the problem is with wiring inside a wall past the jack, you will need a professional to track the break. Your phone company will fix this for a fee.
I hope this helps.