Say, you are on the phone and your conversation partner offers something you first need to discuss with somebody else before you can give an answer. I feel like it sounds unnatural to say "I first need to discuss about this and will couple our decision back to you". There must be other expressions to replace "discuss" and "couple back". My question is: what would be a more proper, natural sounding version of what I just mentioned? And can there also be made a distinction between formal and informal?