Joe ,
Yes, you are correct. There can also be other values that are completely blank which can cause further issues. But for what i was trying to do it was helpful to get an idea for where to start.
Dan's code was helpful for the start, which helped me make labels from Label Expression Window instead of having to maintain a new field. This was mainly for Home Number Label service.
int("".join((i for i in [YourField] if i.isnumeric())))
This expression neglects all the blank values, and the fields without the numbers in them.