I have a box from ATT outside my house with two connections one for the room addition and one for the old part of the house. The Old part of the house is run from the box through a crawl space vent which won't allow it to close. The other is run along the house but exposed. I want to run a wire from the box outside box in a better location to the crawl space and connect both lines so they are concealed and out of the way.

My question is can I remove the phone line connections and than connect them both in the crawl space to a new wire from the phone service and get the same line quality?

Please clarify what you mean by "I want to run a wire from the box outside box in a better location." Do you mean that you will disconnect the two existing extensions from the outside box, run a new line that will come into the house, and then you will splice the two extensions to this new line? If so, then voice quality and DSL capabilities should be fine.

Thanks first for you confirmation that is what I wanted to do. Happy Holidays!