Send text messages over ham radio with the HamMessenger | Arduino Blog
2Pcs 433mhz 1000m Long Distance UART RS232 Data Radio Modem Serial Port RF Transceiver Wireless Transmitter and Receiver Module|rs232|module gprsrs232 null modem adapter - AliExpress
NRF24L01 RF Transceiver Module Communication – Arduino – FactoryForward
MODEM MMDVM ARDUINO SHIELD PCB BOARD RADIO | eBay
How to Use the NRF24l01+ Module with Arduino - In Depth Tutorial