In case of technical or specialist questions, the user can contact the CISP support hotline. This service can be contacted on working days from Monday to Friday, 8:00-16:00 (CET), on +49 (0)30 2598 4436, or any time via e-mail: sendersupport-xrechnung@bdr.de.
Use of this support is subject to the terms of use of the public enquiry service of the Federal Ministry of the Interior and Community.
https://en.e-rechnung-bund.de/e-invoicing-faq/zre/