Ask your provider what type of ISDN switch you will be connected to.
Fax or read the appropriate table to the sales representative.
Ask your provider what additional wiring is necessary to support ISDN on your premises.
Depending on your existing wiring, you might need to have an extra pair of copper wires brought to your premises or additional inside wiring installed. If your ISDN wall jack is an RJ-11 jack (four pins, like a standard telephone jack), use an RJ-11-to-RJ-45 cable. If it is an RJ-45 jack (eight pins), use an RJ-45-to-RJ-45 cable.