Forcing target=_blank in a form submit

I'm thinking of using this simplied version of Vodafone's online text message service in a personal project (I would have to be logged in to Vodafone for it to send an actual SMS but thats not necessary now):

Vodafone Ireland

Recipient

Message

Is there any way to have the form submit to a new window (i.e. _blank) so that when you press submit it opens a new window with the Vodafone response?

What I really want is that you can send an SMS through this form without it linking on to the Vodafone website but I don't think that's possible.

Any suggestions for other approaches I could use?