There are a number of telecom operators (also known as Communication Service Providers or CSPs) who offer data communication between the individual merchants/chains and PBS using the Internet or a closed network, which gives the merchant a number of advantages. The connection between the individual CSP and PBS is a closed network that is duplicated, to provide the best possible operational reliability. The IT installation at PBS is also duplicated and is sited at two different physical locations. The following companies act as telecom operators (CSPs) with PBS:
See the list here
Siminn Danmark A/S The Internet or a closed network are alternatives to a dial-up connection (telephone, ISDN or GSM).