When Verizon pulled the plug on Gene Lew's company, it gave no warning. At first, Lew thought some sort of router had crashed inside the network. "It wasn't until we did a lot of digging," Lew says, "we found out that someone turned the switch off."

Lew is the chief technology officer at HeyWire Business, a 35-person Cambridge, Massachusetts company that gives businesses a way to receive text messages on their toll-free 800 numbers. But when the outage hit on April 3, it temporarily put a stop to that. If anyone tried to text these numbers from a phone on Verizon's network—the second largest in the U.S.—their texts went into a black hole. There was no error message. Nothing.

Then Verizon told HeyWire that it was changing the way it handled the company's traffic. "We were told: 'There's a new set of fees. There's a new set of rules. And you'll have to create a new business relationship to be able to let our customers text your company,'" says Meredith Flynn-Ripley, HeyWire's CEO.

>'It wasn't until we did a lot of digging," Lew says, "we found out that someone turned the switch off.'

For HeyWire Business, that was a big problem. Flynn-Ripley says it was a way for Verizon to squeeze more money out of her company, charging higher fees to have those texts delivered. Citing a non-disclosure agreement, she can't reveal what rules Verizon laid down and what fees the carrier is charging her company, but—more importantly—she says Verizon has unfair control over her how her business operates—and she sees this a violation of net neutrality, the notion that all online traffic should be treated equally.

As the Federal Communications Commission considers new net neutrality regulations for home and business broadband connections—and perhaps even the networks at the heart of the internet—HeyWire Business isn't the only one complaining about this kind of thing. Another texting startup, called Twilio, tells a similar story, and since HeyWire Business's experiences with Verizon in April, the other three big carriers—Sprint, AT&T, and T-Mobile—have all implemented or proposed similar changes, according to service providers interviewed by WIRED.

According to Flynn-Ripley, the problem isn't about the new fees. It's about the control of the SMS texting network that the carriers are starting to assert. "We believe these new rules and fees go well beyond the fast and slow lane debate of net neutrality," says Flynn-Ripley. "This is about operators unilaterally blocking access for individuals or entire... providers with really little or no notice. This is censorship."

Voice communications are covered under the 1934 Telecommunications Act, and by year's end, the FCC is expected to propose new rules governing broadband internet. But SMS is in a kind of no man's land, essentially unregulated, and it is evolving into far more than just a way of sending quick messages to friends and family. Through companies like HeyWire Business, Twilio, Google, and Microsoft, it has evolved into a platform that glues together other applications.

If you've ever texted your Uber or Lyft driver, you've done this because Twilio makes it possible for the two of you to connect over SMS without ever disclosing each other's real telephone number. Home Depot and Shopify use Twilio to build call centers in the cloud.

Twilio CEO Jeff Lawson says the big carriers are laying down new fees and rules to all such text companies—with one exception. The big carriers aren't laying down new fees and rules for each other. "The tier-one carriers have started to add additional costs to messages that go into their networks that they are asking over-the-top companies such as Twilio or HeyWire or Google or Microsoft to pay when the other tier one carriers do not have the same fees," he says.

Last month, Twilio and HeyWire Business—along with a handful of other service providers—met with FCC officials to share their concerns. The FCC declined to comment for this article. But Michael Weinberg, a vice president with communications advocacy group Public Knowledge, believes that with billions of text messages sent every year, the FCC should be paying attention. "It's an important communications platform," he says. "It's often one that's overlooked and dismissed, but it's one that's really critical for a lot of people."

>Twilio CEO Jeff Lawson says the big carriers are laying down new fees and rules to all such text companies—with one exception.

Twilio and HeyWire Business aren't sure why the carriers are changing things up. The only one of the four major US carriers that had any comment for this article was T-Mobile, and they appeared to contradict what Twilio and HeyWire Business told us. "T-Mobile does not charge “Over-the-Top” (OTT) providers for these messages," says T-Mobile spokesman Viet Nguyen. " T-Mobile pays our messaging interoperability gateway partners for enabling this traffic, they do not pay us." Heywire Business says that these gateway providers—companies such as SAP and Syniverse—are passing on the extra charges to them on behalf of carriers such as T-Mobile.

It may be that the big carriers are seeking to squeeze more revenue out of a platform that's on the decline. Increasingly, services such as Google Hangouts, Facebook's WhatsApp, or Apple iMessage are replacing SMS communications with messages that travel over the internet. The telecom analyst firm Ovum says that we are now at peak SMS, and that message volumes will start to decline by 2016.

The new fees and requirements affect one-to-one communications—a consumer sending a text message to a call center, for example. But the carriers have already run afoul of the FCC for the way they manage the five-digit "short code" numbers, used to send bulk SMS messages. In 2007, Verizon blocked messages sent by the abortion rights group, Naral Pro-Choice America. And even today, wine merchants, for example, may be prohibited from talking about alcohol—something that would be a clear net neutrality violation if imposed by a broadband carrier.

That, says Lawson, should give everyone pause, because it offers a glimpse of what the internet could become. "If we don't have some form of net neutrality, the future could look a lot more like SMS, where the carriers get to decide what is an appropriate use case."