https://www.epo.org/en/node/do-i-have-fill-my

Do I have to fill in my telecommunication details, such as phone number, email address or website?

No. Phone and fax numbers, email address and website (URL) are optional. If you consent, these will be published in the searchable database of professional representatives on the EPO website. The fax number is not used for correspondence with the EPO.