Roadsise Assist with InReach device

Don't know about your particular Inreach but mine only sends / receives text messages via satellite, or can act as an EPIRB. (Do NOT use the EPIRB function for breakdowns unless your life is in danger)

Before going bush, you have to setup contacts via your online account, that you can then text message. Then in the event of a remote breakdown, you message them to contact the relevant people for you.

So to clarify - ordinary mobile phone when in range, or the Inreach when remote, by text messaging your previously setup contacts list.

I have a reciprocal agreement with my adult son (we both have a Garmin InReach Explorer).. when he is on a trip he'll message me details of his location, breakdown or issue and I'll coordinate whatever resources necessary to assist him - and keep him updated. He will do the same for me.

I dont think it'd be possible to SMS any of the roadside organisations etc.. best to have a coordinator ready to work on your behalf who you trust.

We've had a HF radio since the early 80's, bought a very early Iridium/Motorola satphone which has been updated over the years, also have one of the first Inreach which no longer works and have carried an epirb/plb since they became available.
The only ever time we had a non repairable vehicle breakdown was a few years ago and the satphone was next to useless for contacting NRMA or in fact any organisation with an automated answering system as the the phone systems can't handle the delay and drops out or puts you back to a repaeat of the menu. Even when a human contact is made they still don't understand the delay and often hang up.
Resorting to the HF and the VKS network had the problem sorted and tilt tray on the way within the hour.
I've subsequently disconnected the satphone due to both increased charges and the need to update the actual phone. The HF is still in the truck and ready to go as required.
I have been looking at a new Inreach mini 2 though.
In my opinion an Inreach type device would be useless for contacting anyone that didn't understand where the message was coming from. Great as a personal PLB and great for the life threatening situation, also good for letting family know you are ok when out of phone range and organising help if required but as has been said you really need a family member or close friend who knows how it all works to organise stuff in relation to large organisations that can help.