So I've enabled XDP on several extensions with Digital PT's and XDP ports. Problem is, when I plug in an slt into the xdp port, I get nothing. Any thoughts on what else to check? Many thanks in advance.

Do you have two pairs cross-connected to each phone? Also, don't forget that the station output from the KSU is for three pairs per station, so you must skip the third pair per station connection.

Hint: The first pair of the station port feeds the XDP jack. The second pair of the station port provides the digital connection between the phone and the KSU.

That should be all that you need.

And check the jack, too. Seen that happen when no XDP was installed or planned. One place I worked only the 2nd pair was X-connected OR landed at the jack. John C.

You were right guys...there was only one pair coming into the phone. I've only used TAW848's up to this point, and a PT simply won't work without 2 pair live into the set so I presumed 2 pair were going into this phone since the Digital set worked fine. Thanks!