they must have some simple code, letters to numbers
Its probably a simple one, but I know nothing of breaking codes. Since these people are stupid, look for the easiest possibilities.
when did she change her profile pic
https://www.theguardian.com/film/2008/nov/14/thriller-ridley-scott
https://www.theatlantic.com/entertainment/archive/2016/07/operation-tinseltown-how-the-cia-manipulates-hollywood/491138/
Do burner phones have the same area codes, in which they are purchased? Or are they assigned randomly? If they are using twitter to send phones numbers for burner phones, then the codes have to be in the tweets.