Verizon Samsung Galazxy S3

[AC Question]

I am trying to convert over to Straight Talk that uses At&t's towers.
My phone is working after changing a setting but there is no data connection
I did the towelroot and rooted the phone downloaded root checker which said it was successful.
tried different APN settings. I am lost!!!!!! Agrrrrrrrrrr...... can anyone please help

 

[sure why not]

Is it even possible for a CDMA phone to get data on a GSM/LTE tower?

Sorry if I can't help, but I'm interested to hear the answer.