Google Voice allows you to send text messages to/from an assigned local telephone number. Unfortunately, it's interface for doing so is rather poor in my opinion. Gmail has a much better interface for chatting and sending text messages.
Unfortunately, Gmail SMS sends messages from a California number instead of my local Google Voice number. It isn't a random number though; it appears to have used the same number for years now. For that reason, I'm unsure if Gmail doesn't support sending SMS text messages using my Google Voice number at all, or my much older Gmail SMS number is taking precedence for some reason.
Can Gmail send text messages using my Google Voice number?
Best Answer
The Email-SMS gateway that Google Voice uses formats email addresses like this in the messages that it sends to you:
12125551212.12015550189.{some-random-string}@txt.voice.google.comThe first phone number there is your own, the second is the other person in the conversation. The random string is just that, a bunch of letters, numbers, and punctuation with no apparent rhyme or reason.
However, this email address is re-usable. I just took a SMS message email that I'd received a couple of days ago and grabbed the address. Then I sent a new email message to that address and the recipient received it as a SMS message from my Google Voice number.
(You can't leave the random string out; it's probably some sort of hash to prevent random SMS sending.)
So, it's no help for the first time you send someone an SMS message, but if they send/reply to you (and you're using the Email-SMS gateway feature of Google Voice) you can save the address used to their contact record and can simply use email to send them SMS in the future.
Note: this only appears to work for the Gmail account associated with the Google Voice account sending the message. (Thank you Larry.)