Our virtual phone network - EPVPN - can be seen as a long term event in between all the other events. Why? Stay connected in between events while keeping your pseudonymity intact.
If an event is running you can call the users on the event by the prefix 09. Users on the event can call the EPVPN users by the prefix 01999.
Users of PSTN numbers may configure 01999 as prefix for eventphone, which is set up to loop back to itself - so e.g. 01999-0310 will be reduced to 0310. This loopback feature comes in handy when configuring devices such as the Fritz!BOX that can switch between VoIP providers based upon different prefix numbers.
The German numbering plan reserves a range (0198 - 0199) as prefix for network internal routing. Thus the prefix 01999 should not conflict with any assigned national prefix. (see https://www.bundesnetzagentur.de/SharedDocs/Downloads/DE/Sachgebiete/Telekommunikation/Unternehmen_Institutionen/Nummerierung/Nummerierungskonzept/Nummerierungskonzept2011pdf.pdf page 83 for further information)
see also: Online EPVPN Phonebook