You want to make on-site reservations possible but you do not have access to internet (e.g. because of a missing telephone or TV connection)? In such a case a mobile hotspot might help. Like that you can set up a WLAN network on your court, which can be used for reservations.
In order to use a mobile hotspot you need an ordinary SIM card for a phone and an internet subscription running on it. Place the SIM card in the mobile hotspot then you can create your WLAN network.
Many telephone companies will provide you with a second SIM card for a reasonable price. If you already have a mobile subscription with unlimited download you can request a second SIM card and use it for the mobile hotspot.