“How many wall jacks will I need for this phone? We currently have a 3-line phone that is using one phone jack. Does this phone work all the lines through one wall jack? The AT&T phone we just had to return had two jacks in the back of the phone, one for lines 1/2 and 3/4. That ment we would have to add a second wall jack in 6 of our offices, Too costly so we returned them. We need a multi line phone only needing one wall jack.”