When importing a list, we strongly suggest that you select "Scrub non-mobile" numbers. Scrubbing is important because organizations are charged full freight for messages sent to non-mobile numbers.
Prompt platform will only scrub a contact one time every six months. So, if you import a list with a contact that has alreasy been scrubbed in the prior six months we won't test that number again. This minimizes the potential scrubbing charges.