In its crackdown on iPhone tethering their phones, AT&T is targeting users who are just heavy data users, says the maker of a popular tethering app.

Mario Ciabarra is CEO and head developer of Intelliborn, the company behind MyWi. MyWi allows owners of jailbroken iPhones to share their mobile data connection with laptops and other devices. Such connections bypass carriers' data plans, or in AT&T's case, continue using the unlimited data plan without paying the $45 for the tethering plan. AT&T is phasing out its unlimited data plan, but those who had it already have been grandfathered in and can continue to use it.

Some connected the recent efforts on the part of AT&T to stop people from tethering their phones to the increased popularity of MyWi and similar apps. AT&T has been sending text messages to users to urge them to upgrade to the tethering plan.

But Ciabarra says that AT&T's efforts have nothing to do with his company's app. Our product is kind of synonymous with tethering, so when tethering users said they were getting these messages, we were automatically connected, Cibarra said.

Many commenters on sites like Modmyi.com have noted AT&T's efforts have not been entirely accurate. Instead, the company has erroneously targeted subscribers who don't tether their devices at all.

Ciabarra sees this as proof that it's not MyWi users that AT&T is targeting, but users who consume an inordinate amount of data. People that use our product happen to be a part of the focus of over usage of AT&T's data network, he said.

Ciabarra notes that for many users who have gotten the messages from AT&T, the cut-off point seems to be 10 gigabytes per month. It is once users reach that point that they attract the attention of AT&T.

MyWi, Ciabarra said, isn't meant to circumvent internet service provider requirements. Instead, the CEO said, the app's main purpose has always been to add features and go beyond the tethering options offered by other companies.

That, he said, hasn't changed with the release of iOS 4.3, which offers connection tethering technology that resembles MiWi's own. Using Personal Hotspot, iPhone 4 users can link their phone's data connection to three devices via a Wi-Fi connection.

But Ciabarra doesn't see a threat in Apple's tethering offering. Noting the lengthy development and testing process that Apple is forced to take with updates to its iOS operating system, Ciabarra believes his company has an edge over Cupertino. We are always going to be ahead of the curve with Apple in terms of features. We will always add value.