Update: did a complete erase and factory reset... twice. It started working again, but quick degraded back to not functioning at all. Here are the details...
First, Verizon support rep stepped me through factory reset and restore from iTunes -- didn't work at all. Verizon's solution: replace my phone with a refurbished model. No way. Mine is brand new. That was unacceptable to me at this time. Maybe later.
Second, I tried a factory reset, but didn't restore -- left it at factory version (8.1 I recall). Went through the new iphone steps, turned wifi and Siri on and... voice control and Siri sorta worked again. It was flaky -- like only 3 out of 4 words, but it sorta worked. I kept playing with it and eventually it started working 100%. Then I did the full restore including update to 8.1.3 expecting it to stop working... but it kept working. Awesome. But it gradually started missing words and then stopped working altogether again. I got maybe 3 text messages and 2 Siri "find location X" map requests in before it started going flaky. Now it's back to as if my microphone isn't working.
I'm not alone here. I see this posted on multiple forums. Yet, the Verizon rep couldn't find any record of it ever happening. I don't see any acknowledgement from Apple that this is an issue. Can anybody shed some insight here? Anything I can try next? Go to the Verizon store? Apple store? A different forum?
Thanks and I apologize for the tone of my responses. This is pretty frustrating. Voice to text was one of the big reasons I upgraded to the 6.