Communication between InReach devices

Sorry if this has been addressed before, but I can’t seem to search the specific InReach forum material. I just recently bought a second InReach so that I would be able to communicate with my home in the event of a loss of phone communications. While I have been able to communicate via text or email to each of the devices, I’m having trouble communicating from one device to the other. Are there any known issues with this and are there any suggestions on what I can do.
Thanks in advance.