> Given there is no mention (that I found anyway) of RCS in the PulseSMS app,
> how else can I be sending/receiving MMS/SMS without any cellular radio on?
I think I figured out why I can Android SMS/MMS on Wi-Fi while others can't.
As I struggle to figure out what RCS gives me that I don't already have,
it's nice that most people seemed to say it's the ability to send/receive
MMS/SMS messages over pure Wi-Fi (i.e., not over any cellular voice/data).
I tested PulseSMS sending on pure Wi-Fi and was surprised it already worked.
Now I need to figure out how that can be when everyone says it can't be.
<
https://home.pulsesms.app/help/>
This question asks specifically the Wi-Fi question I've been pondering:
Q: Can I text when I have a Wi-Fi connection?
(or do I need a connection to my carrier?)
A: At its core, Pulse SMS is just an normal SMS app.
If you have no signal on your phone (zero bars), the app will not be
able to send messages, regardless of what device you are trying to send
from. Your phone must also be turned on, for messages to be sent.
There is one exception to this, but your personal usage may vary.
Some carriers have WiFi Calling that you can enable/disable at the system
level. With some devices and carriers, enabling this will allow you to
send messages over WiFi alone. You will need to test this for yourself,
to see if this functionality works in your situation. I am not able to
provide a complete list of carriers or devices that this will work on.
Luckily, I had already created a one-tap shortcut to Wi-Fi calling settings:
TARGET = com.android.settings.Settings$WifiCallingSettingsActivity
(this is a hidden setting because the non-hidden setting is different)
Where, lo and behold, I happened to have Wi-Fi calling on, by default.
Settings > Connections > Wi-Fi Calling > {on, off} (set to on)
Settings > Connections > Wi-Fi Calling > {Wi-Fi or Cellular preferred}
When I turned Wi-Fi calling off, with both cellular radios off (data &
voice), the PulseSMS text messages failed to send even as the text to speech
worked so I knew I was on the Internet (they sent when I reconnected to
cellular data, so they weren't "lost" but just delayed in sending).
Hence I think I figured out why I can Android SMS/MMS on Wi-Fi.
Apparently Android sent those MMS/SMS texts over "Wi-Fi calling" protocols.