A virtual wireless carrier that doesn’t own its own network but leases service from Sprint, Ring Plus told customers on Friday that they might be cut off as of February 11. Ring Plus said it was in the process of seeking a court order to delay Sprint’s move by at least 30 days.

The announcement came after Ring Plus filed a lawsuit against Sprint (S) last week charging the carrier with fraud, breach of contract, extortion, and patent infringement.

Sprint denied any wrongdoing, explaining it has more than 100 active agreements with other virtual mobile network operators.

“Sprint has fulfilled every aspect of its agreement with RingPlus and we expect the same from our customer,” the company said in a statement to Fortune. “Sprint will do its best to resolve this.”

“We value our relationships with more than 100 MVNOs, and our top priority is to ensure we are delivering high-quality service and support based on each of our agreements,” the company added.

Ring Plus declined to comment to Fortune.

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Ring Plus offers extremely inexpensive mobile plans that supplement Sprint coverage with Wi-Fi based coverage. The company’s innovation in the wireless market is that it also generates revenue by playing advertisements instead of the sound of a phone ringing whenever a customer places a call.

In its lawsuit, filed in U.S. District Court in central California, Ring Plus charges that Sprint has violated two patents it holds concerning providing advertising before a call. And the company said it was tricked by Sprint into entering into a contract to license the technology while Sprint would try to drive it out of business.

“Sprint intended to induce RingPlus’ reliance on its misrepresentations, concealments, and nondisclosures so that Sprint could secure licenses to RingPlus’ patents to avoid paying RingPlus royalties or a lawsuit based on Sprint’s infringing products and services, and to defraud RingPlus to get money,” the company alleged in its lawsuit.