Connect TB400 to ISDN PBX

HI there,

I'm trying to connect a siemens gigaset isdn pbx {3070, used for small businesses) to the TB400. I was told that it should be pretty easy but I cannot seem to get it connected. I want to use the TB400 to make voip calls with the ISDN pbx. I've fysically connected it to BRI port 1 but the leds keep blinking and in the webinterface it gives the status disconnected.

I searched the internet if I should adjust some basic settings but there's not much info about this other than it should connect automatically.

I would appriciate very much if someone could give me some hints or instructions to get this working.

Thanks a lot in advance!

Jan