Basware operates an open network to exchange e-invoices and orders. Anyone can join with an operator as long as the other operator of e-invoices is also willing to be open.
At Basware, it's not just one network within Basware as the network also goes beyond. Some players have their own closed network, and the best way to understand this is the way there are mobile phones and radiophones. As you can call anyone with a phone number, you cannot contact the one who only has a radiophone.