Notice of opposition may also be filed by facsimile. At the invitation of the EPO, written confirmation reproducing the contents of the facsimile and complying with the requirements of the Implementing Regulations - in particular properly signed - must be supplied. If the opponent fails to comply with this invitation in due time, the facsimile is deemed not to have been received (see A-IX, 2.5). The opposition fee must in any case be paid within the opposition period.