First, does another phone get a dial tone at the jack in question? (I prefer an old corded phone for this test since it is unlikely to have some of the problems of a cordless.) Try a new phone cord between the base and the jack. If there is no dial tone, try the test phone at other jacks. If there is no dial tone at any jack with either phone, find where your telephone service comes in and open the service box. If you are lucky and have a fairly new connection, the service box will have RJ-11 jacks. Plug your test phone into the jack and check for dial tone. Otherwise you will need the phone company to do this test. If there is no dial tone at the service box, your phone company will fix the problem for you for free.
If your test phone works:
Make sure that the base is plugged into a working outlet (no tripped circuit breaker, turned off power strip). Next check that the handsets are registered with the base. To register the handset, press the Find HS button on the base (below the in use indicator) for 4 seconds, then press # on the handset. (Our cordless phones once lost their registration during an extended power outage.) You can force deregistration by pressing and holding Find HS for 10 seconds. The In Use light should come on and flash. Then release the Find HS button and then press and release it again while the In Use light is blinking. You may need to try unplugging the base after pressing Flash/Talk and then Off/Clear before deregistering the handsets. The register the handsets.
You can Mute the microphone on the handset with the Mute button. To silence the ringer, press Menu/Select when the handset is not in use. Use the up/down arrow keys to select Ringers then press Menu/Select. Then press Menu/Select to choose Ringer Volume. Use the up/down arrows to change the volume and then press Menu/Select to confirm and save the setting. This should not change the ability to hear the dial tone.
If your test phone works at the service connection but nowhere else, then you have a wiring problem inside. Check exposed wires if you have them. Your phone company will offer to fix the issue for a fee. If the problem is at one jack, open the faceplate and check for loose wires. Some faceplates use a keystone with a punch-down tool to secure the wires. Others just wrap the wire around a screw for each pin.
If the handsets are registered and the base has power, then the cordless phone has problems. If it is under warranty, have it fixed. Otherwise, replace it; they aren't made to be user serviced.
The manual is available here: http://www.vtechcanada.com/support_docs/vtt/CS/CS6319_en_cib.pdf
I hope this helps.