Dtac. You can even keep your number while no longer in Thailand. I return to my home in the South of France for 6-months each year without issue. Great coverage, easy to use phone app and affordable.
Log on to your application, that is the only way to find out current status. HCMC Thai Embassy are very slow. 5 day reset, each time they ask for additional paperwork
I showed three years of trading accounts and fully paid tax returns with ample available funds, but got rejected. For whatever reason, they need funds to be shown in a traditional bank account in your own name.
I was told the same thing by IO at BKK, and even had to sign a form stating that I understood. I am in HCMC, so applied online here, but it is taking forever. 10 days already. They have asked for extra documents. Proof of accommodation for whole 60-day duration, whereas, I had supplied proof of first few days, and then condo booking for final 30-days, as I wanted the freedom to move around Thailand. They have also taken issue, that my inbound and outbound flights are not on the same booking, although both are with Vietnam Airlines. Stressful! Good luck, but I certainly would just arrive hoping to get in via a visa exempt.