Best Coverage
You will note that AT&T and its MVNO's (mobile virtual network operators) wireless plans have the best coverage on the OT of south eastern and south central Missouri while Verizon has the best coverage on the BRT, OHT, and ONRT of Arkansas and the OT North Fork section according to the FCC.
FCC 4G LTE Coverage
There is no coverage in the National forests with the AT&T prepaid plans. T-Mobile is coming on strong in so far as coverage is concerned but you will note in the coverage map below coverage in the National Forest is by a partner.
Regardless, connections are only possible on the ridge tops in the National Forest.
Here are coverage maps from the carriers.
T-Mobile 5G and 4G LTE Coverage
Verizon 5G and 4G LTE Coverage
AT&T 5G and 4G LTE Coverage
MVNO (mobile virtual network operators) Coverage Maps
SEARCH for nearest city and zoom to find trail on USGS National map base layer then select carrier to see signal. NOTE: A Text message connection will sometimes be made (but don't count on it to send immediately. The phone will continue to attempt a connection and send and receive text messages as you hike.) when voice and data connection will not.
You should consider packing an Iridium satellite Global 2-way text device (Zoleo or Inreach) which will send your GPS location in the body of the text message via the satellite and in the SOS. The message is not sent immediately but rather the satellite is polled every 10 minutes or so (according to a device option) to send an receive messages.