from my limited knowlege on vocoders, I believe this is correct EVRC is 3G, IS96 is 2G, and 13k Voice is analog...
EVRC, SMV, EVRC-B, and all fall into this catagory, EVERC-B being the successor and is a 3G codec
IS-96, IS-96A fall into this catagory IS-96A being the successor and is a 2G codec
Voice 13k, and Voice 13k- IS733 fall into this catagory IS733 being the successor.
my guess is that EVRC-B is your best bet, but also use trial and error, try the successor of each catagory and post back with results, I'm curious as to what you will find.