ISDN Phone

What do you mean with "ISDN numbers"?

Do you want a simple ISDN extension or a ISDN trunk (e.g. CO-trunk)?
If you want a ext., you have to know if you want a point-to-point or a point-to-multipoint (bus) configuration.

When I saw the title of this post I thought it referred to legacy AT&T ISDN multi-line phones, using 2B+D.
I'll still occasionally get a request to multipoint one with an existing phone on the LEN. Those require a SPID.

Siemens does have an ISDN station option or card? I wonder what kind of phone would be used?

Many tks all!
I want a simple ISDN extension
I use the phone as attached pictures
Tks

STMD module was mainly used for ISDN trunks but can be configured for non-buspowered phones too. As there were not many pure isdn phones on the market, the subscriber option was used mostly for isdn videoconference systems or servers with isdn cards.
In fact this was long time before all of this functionalities were moved to ip/internet.
In central europe ISDN is dead, even co trunks are sip based nowadays - the STMD modules are kind of obsolete.

For example
ADD-SBCSU:11200,FBUS,DIR,1-21-2-0,SET600&DTE,3,3,2,2,1,1,0,0,N,0,0,,,SBDSS1,,SBDSS1,Y,Y,0,,,,,Y,N,N,,5,0,,;
ADD-SBCSU:11201,MSN,11200,,3,3,2,2,1,1,0,N,0,0,,,Y,N,N,5,,,,,,,,,,;