With ISDN30e you can have up to 5 layers of DDI numbers. The layers can either be single numbers or DDI ranges. DDI ranges are supplied in blocks of 10, but can be anything (i.e. 100s or 1000s). The maximum number of layers is 5. All numbers are applied consistently to all channels.
For example, 5 layers shared over all channels. On an ISDN30e setup, what applies to one channel applies to them all: