[Zope] sending SMS messages from Zope application

Hi zopistas-out-there, I want to send SMS messages (several hundreds every few weeks) from a Zope application. Do you know of some way to do this? I prefer not to use a SMS service provider, because of the huge step-in costs. So I think about modeming to the SMS gateway of KPN or Vodafone (I am dutch), which I can reach by GSM phone number. I want to send several messages (the same message to several people) in one call. Thanks, Wout Tankink