I can make calls but phone doe not ring

You said "it seems to ring once then stops." One possible cause of what you're describing is called a "Ring Trip." It is characterized when the button that flashes to indicate an incoming call changes to steady red (which would normally indicate the call is answered) although no one actually answered the call. If that occurs, then you have to test to see whether you can tell where the problem is coming from. If you unplug all the phones, you can then call in (from a cell phone or other phone that's not part of the system) and see if the incoming call rings unanswered, as it should when no phones are attached. If all rings in OK, plug just one phone in at a time and call in to see if any particular phone causes the problem. If one causes the ring trip, then disconnect that broken phone. If ringing still stops when no phones are attached, you'll have to disconnect the phones' connection wires (Station Wires) at the phone system box that plug into the "Station Ports" (label them before you unplug any!). Do not unplug the plugs for the wires that feed phone company lines into the phone system, the jacks are called CO line ports. With the "Station" wires unplugged, see if If all rings in OK by calling in from a cell phone or other phone that's not part of the system. If all rings in OK, plug just one station wire in at a time to see if one causes the problem. If one station wire causes the ring trip, then disconnect that troublesome wire and inspect its "system box jack" and its phone jack for water damage, carpet cleaning solvent, exterminator spray or any other corrosive liquid damage. Sometimes a staple through a wire where there's humidity can cause the problem. This process will find the offending wire, jack or phone that causes a "Ring Trip." There are many other possibilities, but the extremely limited description you've provided "it seems to ring once then stops." doesn't help me send you a better answer yet.