I have an Omega2 with the Hologram.io shield (which has a ublox SARA-U201 chip on it). It was working fine when I noticed yesterday it wasn't online anymore. With some digging, I found that the chat script was failing because suddenly the ATDT99**1# is returning ERROR when it was called in the chat script. I've tried issuing an ATZ and an AT&F0, tried using AT&D0 in case it was RTS related.
The chat script is rather basic, just doing an AT check for OK before dialing. And was working for the past two years (although I only use the omega2 seldomly). I have no clue what may have suddenly changed. Checking the hologram website, it doesn't appear that there's any problem with my account or a data balance or anything.
Any suggestions on what changed and/or how to fix it?