I tried SOS Messaging during the Verizon outage, but it did not work

During the Verizon outage yesterday (9/30.24) I thought it was a good time to try out SOS Messaging. I successfully connected to the satellite, and it said I was ready to send messages, location, etc. but every time I attempted to send a Message I immediately got a Message Not Sent indication.

Was this due to a massive number of people trying to use the SOS Messaging function or is it indicative of another issue?

I ask as I frequently travel in areas not coverage by the cellular network and want to know if I can count on SOS Messaging.