if you return on the same day you are trying to live here on a tourist visa and they will take you to a room and question you about that. If your passport is full of Thailand tourist visa & visa exception stamps they may deny entry.
The real answer is you need to go to another country for 10 to 30 days to prove your not trying to live in Thailand; Everything becomes easy after that
I have a second cellphone I use as a wifi hotspot for my us phone. My tello and mint do wifi calling back to the USA for 0 extra. If I want to call local use line or for real call I need to add talk time to plan, as I only have $10 a month data on the AIS sim