Sony Videoconference ISDN

[rapzap]

Hello,
At my work place we have a old video-conference device Sony PCS1600, and I want to connect it to ISDN port and it does not work.
The device has 3 ISDN port connections on it, the question is it's necessary to install a ISDN box converter in front of the device and from that box to go in Sony, or the Sony has this integrated and converts the signal that comes directly from the provider??

 

[rfpup]

I have tandberg video-conference device, It has also four ISDN BRI ports (S0 ports) and for having successful connections you need the following:
PSTN -> NT terminal -> Video Conf. (NT terminal being connected via two wire coming from PSTN and one of four wire ports (S0 port) of NT terminal connected to Video Conf (3,6 &4,5 are Tx and Rx of ISDN line)
when interconnecting NT with Video Conf keep in mind that Tx of NT is being connected with Rx of Video Conf and vice-versa.
Check in the manual the pins of S0 ports for NT and Video Conf

Then it should work.