As they are different accounts then your husband will need to obtain a PAC code to take his number away from Virgin. He will need a cheap PAYG SIM from a different provider and use the code to transfer the number to that.
Once done he then needs a PAC code from the new provider which you can give to Virgin to bring the number in to the Oomph account.
I'm a Very Insightful Person, I'm here to share knowledge, I don't work for Virgin Media. Learn more
Have I helped? Click Mark as Helpful Answer or use Kudos to say thanks