TIBBS
Technology writer Ron Albright wrote of several BBS applications written for the TI-99/4A in the March 1985 article Touring The Boards in the monthly TI-99/4A magazine MICROpendium. While Albright's article references several notable bulletin board systems, it does not confirm what was the first BBS system written for the TI-99/4A.
Read more about Tibbs.