Connect Cat6 Cable From Ext Nte To ADSL Nexuslink 5631 Router?

I am trying to connect a cat 6 cable from the Ext Nte to the adsl nexuslink 5631 router but i couldn't make the router works for the 2 line i only get one line led on i tried to change the wires colors on the rj11 (4 pins) and even so i cloud not get both led light goes on for tho line and this only for the cat 6 if i hook the old wire i dont know whats kind of wire i think its for inercom or mebe cat3 its works in the ext Bt only 2 wires connected and on the modem side 4 wires is o nthe rj11 plug i tried to do it the same way with cat6 i only get single line and i do it now with (white-orange=pin 1) (blue-white=pin 2) (white-blue=pin 3) (orange-white=pin 4 ) on the plug , on the bt side i tried to but white -blue with blue-white not working even the opposite.i just want to know how to wire from ext-Bt to router using rj11-4pin cua thats what my router use on bonding to lines, btw i have only 2 wire on the bt side because i got 2 line phones on a phone line in the bt?