While the main intended use-case for the cellular connection is the use of high-speed mobile data, this is very likely possible by sending AT commands from the Omega to the cellular modem. I would recommend looking for the AT command reference for the EC25 cellular modem.
An alternative to sending SMS messages directly from the Omega2 LTE would be to use the data connection to communicate with an online service like Twilio to programatically send text messages.
Omega2 & Omega2S
Correct, the surface-mount Omega2S is a repackaged version of the through-hole Omega2. Think of it as a super-set of the through-hole version, check out our documentation for a full list of the differences between the two models.
Regarding the +/non-plus variants, it refers to the amount of memory and storage, no difference in the pinout.
The hardware reset pin is available on all of the models. Look for the pin labelled
RST on the pin-out diagrams.
Watchdog & Unattended Operation
For more info on using the watchdog, please consult the MT7688 datasheet. There are 3 registers that control the watchdog's operation, you can configure them through the
/dev/mem device, or using the
devmem program. You'll also need to look at the
GPIO1_MODE register to adjust the pin multiplexing so that the WDT signal is brought out to the pins.
You'll have to ask the OpenWRT developers about the stability of init.d :)
FWIW, we've never seen any major stability issues in our experience.