Phone systems always get overloaded after an earthquake.
After the 1989 Loma Prieta quake, I picked up the landline phone and didn’t have a dial tone. The switch does not send dial tone until connection equipment is available for your line. I had to wait 30-60 seconds to get a dial tone.
Cell networks also get overloaded. An SMS message usually gets through because that only needs a tiny slice of resource, far less than a voice call.
In 1965, we lived in Baton Rouge when Hurricane Betsy came through. That dropped a lot of limbs and trees on a lot of utility lines. During the storm, we could hear the “boom” as power substations failed. Phones were out for seven days, power for ten days. If that happened these days, I’d be pretty excited about a week without RFI.
Pedantic alert.
Whilst there’s nothing to stop you carrying an EPIRB instead of a PLB, they generally tend to be bigger, heavier and more expensive. EPIRBs are normally regarded as boat (or life raft) equipment, whereas PLBs (the clue is in the name - personal locator beacons) are more suited to what we are discussing (IMHO).
The next generation of PLBs being designed for use with MEOSAR satellites are likely to have some limited degree of 2-way comms (e.g. Return confirmation that your distress signal has been received).
A PLB connects directly to the regional RCC, the emergency services. It also has a homing signal so your mountain or what ever rescue team can using direction finding methods to locate you. A Sat phone when you call the emergency services connects you directly to them. In another incident I had a rescue helicopter call me on my phone when they were in the area to pin point us and let us know when to let off the orange smoke flares, so yes we were in direct contact with the mountain rescue team locating us.
Today’s outage of the database server is a perfect example of why expecting to be able to send SOS messages through the infrastructure is unwise. The current problem is a hardware fault with a server at the hosting company. We pay a reasonable amount for, in my opinion, exceptional service. But it is not fault-tolerant or auto fail-over. The service uptime is way beyond what we need for some hobby services but is not suitable for SOS services by a huge margin.