Premise: One wire coming in with 2 wiring pairs: one pair red-green, the other pair yellow-black.
The wall plate would need to have two (dual) ports.
Most likely, for a dual port RJ-11 wall jack, you would wire the red-green pair to one of the ports for telephone/voice.
Then wire the yellow-black pair to the other port for the DSL connection.
Something like the splitter diagram in the upper left part of the link.....
The requirement being that the incoming wire is configured that way at its point of origin or somewhere else along the way. Possibly all the way back at the connection point where service first enters the dwelling. Normally everything downstream from that point is the responsibility of the residents. Either DIY...