An NTRIP modem is an very easy method of getting NTRIP correction messages to a rover.
An NTRIP modem in essence consists of a wireless connection (typically cellular 4G/LTE) and an NTRIP client which can connect to an NTRIP provider. Additionally such a modem typically features an RS232 port on which the RTCM messages are outputted. This port then needs to be connected to the rover.
Examples of commercially available NTRIP modems are: