I suggest you verify the IW with a Tempo Sidekick 7b prior to completing the installation. This meter can help identify a cross, short, open, etc... I also suggest to make sure the polarity for tip and ring on the unshielded twisted pair is correct. Most phones and faxes have polarity gaurds now days, but it doesn't hurt to rule everything out.
This is CABL.com posting #170145. Tiny Link: cabl.co/mSqr