My phone says parallel set on how i fix it - Vtech 5.8GHz Cordless Phone with Digital Answering System

I assume you cannot get dial tone on your Vtech handsets or base unit. The phone is telling you that another phone or device has seized the line, therefore it cannot give you dialtone. You could have another phone or device(fax, modem, etc.) off hook or you could have trouble on the line caused by bad wiring, faulty line cord, or bad outlets. To find the trouble, you need to remove all devices from all outlets and try to isolate the bad wiring, line cord or outlet by connecting a standard good phone to one outlet at a time using a known good line cord. If you are unable to isolate the trouble using this method, try going to the outside interface box and testing the line there. Inside the outside interface box there is normally a test jack with a short line cord plugged into it, unplug the test jack and plug your standard phone into the test jack. If you don't get good dialtone then the trouble is with the service provider and you need to report it to your service provider. If you do get good dial tone then the trouble is in the building wiring, outlets or phone devices. Typically there is more than one pair of feed wires from the interface box to the building outlets. Remove all but one pair, then go inside and check all outlets for dialtone(plug standard phone into each outlet one at a time) to find which are connected to the pair of wires that are still connected at the interface box. If you find trouble on this feed wire( can't get dialtone at any of the outlets), remove it at the interface box and connect a different pair of feed wires, go inside and test all outlets again. If a feed wire tests good(you get dialtone on at least one outlet) then do not remove that feed wire at the interface box and just add the next one at the connection terminals in the interface box then retest your outlets again. Work your way through all of the feed wires and outlets in this manner to isolate where the trouble is. A bad wire, line cord, outlet or phone can produce a short or partial short across the telephone wire pair that will appear to your Vtech phone as if a parallel set is in use. It can sometimes take quite an effort to locate a bad wire or outlet. Good luck.