Outdoor Phone line help!?

I have an outbuilding i’d like to run a phone line connector from the socket so I can have my modem/router in the outbuilding, some 25 meters away. I’m looking at getting a premade cat6 ethernet cable external, with RJ11 plugs.Will this work well without any degrade in quality etc? The cable will be ran through the garden. via /r/tech https://ift.tt/2NvRc3c