If your home was wired to standards you would need to connect the White/Blue pair to the incoming service. The incoming service should include a network interface device (NID) which should have the line marked as line 1 on the customer side of the interface access door. This may be marked with either Green & Red posts or id'ed as Line 1. If you have a 2nd line it would be on the Yellow-Black or Line 2. As residences are to wired to T568A standards, the 2nd line on the jack of your category 5e wiring would then be the White/Orange pair at the jack.
Joseph Golan, RCDD