Setting up and programming the DTR-4-1 Cordless?

By default the cordless phone mirrors line keys 1 thru 4 on the button programming for the ext. in 9000. You can do one of two things.....Change the button config. in 9000 to put your prime line and virtual, etc. on lines 1 thru 4, or program the cordless to tell it (as an example) F1 is LK16, F2 in LK15, F3 is LK3, or what ever. The instructions to program the cordless are as follows:

SECTION 2 SETTING UP AND PROGRAMMING THE DTR-4R-1
Programming Mode
1. Press and hold down * and #, then press the TALK key. The F1 LED
flashes red.
2. Press the R/VOL key repeatedly to scroll through the line key (LK) and
feature options for function key F1.
3. Press the MUTE key to select the displayed line key or feature.
4. Press the R/VOL key to toggle between æTALKÆ for On or æNO TALKÆ for Off.
æTALKÆ is selected when the F1~F4 function keys are programmed for
CO or Call Appearance Keys. æNO TALKÆ is selected when F1~F4
function keys are programmed for functions not requiring an off-hook
state (e.g., Log On/Off or DND).
5. Press the MUTE key to advance to the next function key (F2 ~ F4).
6. After programming F4, press the MUTE key to advance to global off-hook
ringing assignment.
7. Press R/VOL to turn global off-hook ringing on or off (LCD indicates ON or
OFF as appropriate).
8. Press the TALK key to exit.
Function keys (F1 ~ F4) can be programmed as line keys 1~16 for
redial (LNR/SPD), answer (ANS), feature (FNC), or recall. When
assigned, these keys operate the same as on an NEC multiline
telephone.
When initially installed, function keys (F1~F4) default to line keys 1~4
respectively and off-hook ringing defaults to ON.
Global off-hook ringing must be set to ON (default) if any function key
is to operate with off-hook ringing.