When Memory Block 4-47 (ISDN Directory Number Selection) is assigned as YES, and Memory
Block 4-62 (ISDN-PRI Directory Number Selection) has a number assigned, the setting in Memory
Block 4-62 overrides the number set in Memory block 3-52 (ISDN Trunk Directory Number
Assignment) when the station places an outgoing call using PRI. PRT Firmware 2.12 or higher is
required.