APRS TOOLS TOOLS when you come to the APATS TOOLS AND APRS MESSAGE BOX tab
WHAT IS THE APRS SYSTEM? if the APRS system using mobile device can work bidirectionally, that is, it can send and receive messages; Mutual Messaging, You can even email. The system is known for all mobile devices with APRS, handheld devices and computers.
If you have a device like TM-D700, TM-D710, FTM350, VX-8, TH-D72 with some APRS feature, you can see it as a message on the device screens without the need for internet.