Cellular Data Number is "Unknown" on some iPads Dealing with numerous iPads (3G and LTE), all with the same telco.

If I go to Settings, General, Cellular Data Number, some iPads display the number fine (e.g. +11234567890).

On others, it shows "Unknown"

There doesn't seem to be any pattern or any rhyme/reason to it (e.g. iPad model, iOS version, SIM card age). Some show up, others don't.

The only fix I've discovered is to have the telco "push an updated profile" to it (not an "iProfile" - some sort of telco profile).

This fix works (after a device restart) but I'm wondering if anybody else has encountered this and found a way to avoid the problem in the first place?
This occurred when cellular data was turned Off.  I turned it on and the number appeared.