I searched alot and tried in a test lab before question but can't find the answer
I want to update just all directory numbers (Extension) of exact device type on CUCM
How can I accomplish this with bulk as I can't find this field in update lines and I don't want to delete and import the phones again
There should be a way to do this via a Custom File Format. Can you tell us which field on the DN you want to change?
Another quick way (if it is feasible in your environment) would be to move all of the phones of that type into a temporary device pool. Then you can search for your DNs in Bulk Admin - Update Lines where your search for DNs is via Device Pool. Then make the change. Then move the phones back. That would work best if there are only a few device pools in your organization, of course.
I want to edit the extension itself not anything more
I was using extension mobility and most of The directory number field is blank in phones so when I made bulk insert phones all detail I get failed process
it just update existing DN and not fill the blank ones
You'll have to do so with the custom file, you cannot do that with the BAT interface directly using the search option.