No experience with the Regal, but I have learned recently that many cell devices use 2G old cell phone signals. AT&T will be dropping all 2G coverage at the end of the year. Other carriers may pick up or extend 2G coverage past then...
The company advertising here, also the system I use told me they will be upgrading theirs to 4G. And I hope it is reasonable priced or free.
So my advice is buy a 4G device if possible...
Phillip does air to air photos DBA; Pilot Portraits. And makes the Switchbox.
EAA magazine about 3 months ago did a good review of his and two others for comparison.
I have an AT&T SIM card currently. The quick fix is to replace it with T-Mobile, but we don't have such good reception and someday they too will drop 2G I believe.
You can buy the sim card from best buy for $5 then you just go to tmobiles website and enter the sim card info and select the $3 prepaid plan. It includes 30 minutes of talk or 30 texts. You have to put a minimum of $10 on the card so that covers 3 months.