Multiple users have complained that Google Voice forgoes defaults to send text messages through their standard SMS app -- and subsequently, from their carrier number. For example, set your Google Voice number as the default SMS number in Hangouts, then set Hangouts as your default SMS app, and when you say "OK Google, send a text", it ignores everything and sends it as a regular message. This makes it difficult to keep track of where your messages actually are, plus it reveals your regular number to people who you might not want to have it, or to people who don't have it and wonder who the message is from. Confusing.
But after one irked user reached out to Google Voice product manager Jan Jedrzejowicz on Twitter, it seems help is on the horizon. In reply, Jedrzejowicz tweeted: "'OK Google, send a Google Voice message' coming soon to GV, this will help". It's not clear yet exactly how or when it will help (we've contacted Google for more information and will update this article accordingly), but users will be relieved to know the issue is on Google's radar.