Register DDI to a group

[Sebiiiii]

Hello World !

I'm very new in OXO / OXE, and I try to figure out some basics, but even if I search for a week now, the truth is I don't get it.
Also, my OXO / OMC is in french (sorry for my poor english)

So, here is the plot :
For several reasons, I have to cold reset this OXO.
I did basic reconfiguration, so, it works.
But, here the twist
I have 3 DDI, which are not sequencials.
Where do I declare those DDI ?
I need it to assign one on them to a group of phones, and external calls must show this number.
Actually, external calls show head DDI, not the DDI I choose.
So, where do I declare this ?

Thanks for your help