Ok, real world examples:
1) I'm playing a custom race, which gets UT as a starting tech, and I meet the Thalan (who don't have UT as a starting tech). They haven't researched UT yet. I'm able to talk with them.
2) I'm playing the Thalan, and I haven't researched UT yet. I meet the Terrans, who do have UT. I'm not able to talk with them.
Based on #1, it would seem that the races can communicate when either one of them has UT (it's not required by both sides). But when I'm the one without UT, I still can't communicate.
So what's the deal? Is this a tech that's essentially useless for the AI but required for me?