Hi Ranti -
Enterprise customers pay a monthly license fee which generally starts at $1500 monthly, so we should find out whether you really need that service.
You can make additional campaigns through the developer Dashboard GUI (but not programmatically) at no cost. If all you need are a few campaigns, this is the way to go!
If you are ready to talk about a dedicated short code (which is a great idea) let me know and we'll get started on provisioning you a dedicated shortcode and that would come with an enterprise account, access to the enterprise account management GUI, and more.
Maybe let me know (offline) a bit more about your needs and timeline, and I'll make sure you get what you need.
Anthony