Leaving SMART and coming back within a month

Hi SMARTY

My husband decided to leave SMARTY as the Wifi calling toggling was losing calls - his number was an additional plan on my account in my dashboard.
He has done so - but the other network said they have "Wifi Calling" but it has not materialised and the optiona is not available on that other network despite being advertised as a standard feature.

Question - is it possible for him to come back to SMARTY on my dashboard/account within a month with his original number via a PAC code?

Cheers 

Jackie