Innerfence founders Derek Del Conte and Ryan Johnson got a disturbing email and phone call from Google yesterday. The search giant notified the Seattle developers that the company's popular iPhone text messaging application, Infinite SMS, would no longer be supported because it was flooding the experimental Google Talk SMS service with too many users.

"We never could have guessed that the two of us would write an app too big for Google," Del Conte said in a message on the company's Web site. In an interview, Del Conte said they decided yesterday to remove the 99 cent application from the app store. That was an especially painful move since the product -- which uses Google's instant messaging service to send unlimited, free text messages -- had become the 11th most popular paid application for the iPhone.

Del Conte is perplexed by the entire matter since he built the application using the open protocols provided by Google. Infinite SMS  attracted "tens of thousands" of users, he said.

"Other non-Google apps have been able to access the SMS feature since its launch," wrote Del Conte. "To us, this was no different from accessing Gmail’s near limitless storage over the open IMAP protocol."

Del Conte said that Google sent an email message explaining the decision yesterday, though he still has other unanswered questions. This morning, he receive another message saying the feature would be turned off tomorrow. In yesterday's message, Google wrote:

"Infinite SMS is a third party app that has been using Google technology to provide free SMS for users, while we were paying for the cost of the text messages. While Google is supportive of third party apps, we've decided we can't support this particular usage of our system at this time. SMS chat is still just an experiment in the early testing stages in Gmail Labs. We're blocking all external XMPP clients from sending SMS; we're not singling out Inner Fence."

In my story on Infinite SMS last month, I raised a question about whether Apple or AT&T would support an application that essentially allowed text messages to be sent for free. (Del Conte didn't foresee problems.) At the time, I didn't think to ask if Google would object. 

Del Conte is still trying to figure out what it means for his business and whether Infinite SMS is dead for good. And he's pained that he can't offer a refund, something he says Apple doesn't allow in the app store.

"Obviously, we are disappointed," he said. "But beyond that, I am not sure there is much more to say."