How to conference call on a nec dtu 32d 1a phone?

Yes, the NEC DTU-16D-1A can be used with a standard PSTN line. You will need to program the phone system to recognize the PSTN line instead of the ISDN2 line. Here are some steps you can take:

1. Access the programming mode on the NEC Xen Alpha system by pressing "Speaker" and then "7" on the main phone.
2. Enter the system password, which should be provided in the user manual or by your system administrator.
3. Press "Speaker" and then "3" to enter the line programming mode.
4. Scroll through the line options using the arrow keys until you find the option for PSTN. Select this option.
5. Save your changes by pressing "Speaker" and then "Store".

Once you have completed these steps, your NEC DTU-16D-1A handsets should be able to connect to the PSTN line and function properly.

If you go online and type in your system type/user guide/PDF, some service companies have the user guide online for download.

I'm showing your problem in the cell phone category but I guess we are talking about an office phone set up. There should be a way to just pick up the phone when another co-worker is doing a training call by pressing the button for the line he is using. If not then perhaps the manual suggests a way to set up a conference call.

hit feature key,hit a line key,dial 9 plus the number,hit feature

you need to remove ringing programming in 4-01 for that extension. ldtsnj.com

CHECK NEC AMERICA WEBSITE

Yes while the phone is ringing use the down arrow key and it will lower the volume.

As an FYI....The arrow keys control many things,
If not in use, they control the contrast.
If ringing, it adjusts ringing.
when using handset or speaker, it adjusts volume.

do you have VM on this system?

Press Feature 1 That will turn the mic off, or on.