rewire master box ?

i recently installed sky tv and the engineer could not get me configured properly as the line continally said it was busy . looking at my phone line i still have the old fashioned small grey ovel sort of box sky enginer reckons i should have a new master box . i already have a new master box connected but i fear maybe i should have done away with the old box first is it ok for me to re wire as ther is only two wires going into the old box but the master box has room for many wires i know to use 2 3 and 5 can you advise how to take out the old to wire into the master box