Adding a phone number to a pre-existing SMS Campaign

[CrisTandT]

Hello,
I am our account admin. We have an SMS Campaign established which is not full. We have one phone number that requires to be added to it, but every time I go through the steps to add it, it gives me the message that it takes 24 hours. So I check back and it's still unverified. Can you add numbers to a pre-existing SMS Campaign? If so, any thoughts on why this one number (that has been a part of our system for a long time) won't add?

Thanks 

[Nisha1]

Try removing and re-adding the number to reset any glitches. If that doesn't work, check for alternative verification methods or account restrictions.