Thanks for the reply alfick3.
The APN is set up and I have searched on line about MMS on AT&T. I have also called ST support several times. They have been surprisingly helpful but unable to make texitng work. My APN settings are:
Name: Straight Talk
APN: tfdata
Port: 80
MMSC:
http://mms-tf.net
MMS proxy: mms3.tracfone.com
MMS port: 80
ST says the sim card is set up for LTE.
From what I can find on line it appears that MMS requires LTE on AT&T service.
I would appreciate any additional suggestions.