As far as I can see page or paragraph numbering is not a feature supported natively in the epub format.
However Adobe has designed a add-on feature to the format that would support page numbers set by the publisher. For further details see the
EPUB Best Practices Guide published by Adobe (requires an epub reader)
Further
a survey sponsored by the Open eBook Forum (now IDPF?) of 2002 shows that page numbering is the no 6th most wanted feature of for ebooks. What kind of numbering is not mentioned.