One ring - noise like fax to caller, phantom call to receiver

Best to visit this page to find the manual you are after.

http://www.uniden.com/telephones/dect-60-cordless-digital-answering-system-with-caller-id-expandable-up-to-6-handsets/invt/dect1580g

http://www.uniden.com/accessory-handset+charger-for-dect1500-dect-60-cordless-phone-series/invt/dcx150g

If you have a landline, most likely you have a short in it. Not enough to kill line, but, when the 90 volts a.c. comes in to ring it jumps short. The short answers the phone.. It doesn't stop out going but can cause static. Check the line at the box outside. if bad there call your phone company, if good there, trouble is in house

See http://www.timewarnercable.com/en/residential-home/support/topics/phone/caller-id-and-calling-features.html

The call forwarding instructions start just below the middle of the page.

it could be an outside trouble on your telephone line that will only effect certain features

Since you declined to specify the model of your Uniden DECT 6.0 system I can only suggest you select it from the list beginning here to download a copy of the manual.

the tiny indent under the "DECT 6.0" decal is the microphone- check to clean any crumbs/gunk from that crevice.

Setting the Number of Rings (Excerpt from the Uniden Dect 1580 Phone manual

The ring time setting allows you to set the number of rings the caller hears before your answering system plays the outgoing message. You can set the ring time to answer after two, four, or six rings. If you enable the Toll Saver (TS) setting, the answering system picks up after two rings if you have new messages, and after four rings if there are
none. This way, if you make a long distance call to check your messages, you can hang up after the third ring to avoid long distance billing charges.

1. Press Menu/Select.
2. Select the Ans. Setup menu, and then the Ring Time submenu.
3. Move the cursor to select a ring time (Toll Saver, 2 Times, 4 Times, or 6 Times).
4. Press Menu/Select. You will hear a confirmation tone.

The problem may be a short on your line. (Have the local Teleco check your line.) If you have other phones, you may want to check them for dial tone(DT) when this happens. If you have no DT, your cordless may be the problem...unplug, and let charge overnight. If problem continues, replace the battery in cordless, or discontinue use.

These DECT 6.0 phones work on 1.9 Ghz frequency and should not have any interference other than from another DECT 6.0 phone that can be within 150 ft of your phone. That means that somebody, a neighbor that has a DECT 6.0 phone close by is causing this problem. It also means that they are also getting these phantom phone rings. The best solution? Go to a 5.8 Ghz phone and your problem should go away.