Litigators and professional plaintiffs employ a variety of tricks in order to entrap callers into Telephone Consumer Protection Act (TCPA) and Do Not Call (DNC) list violations. One of the most dangerous ploys is also one of the simplest: the dual-purpose phone line.

Sometimes referred to as “mixed-use” lines, the deal-purpose line gambit works as follows: Litigators will use one phone number for both business and personal purposes, potentially entrapping marketers who believe they are making calls to a business line when, in fact, it is a personal line for TCPA purposes.

These numbers may be listed as business numbers on the plaintiff’s website or even listed in a business directory. But if the numbers can plausibly be claimed as residential or personal phone numbers as well—perhaps due to the business being run out of a home office—then any calls placed to that number under the auspices of a legal marketing call to a business may run afoul of the generally more stringent restrictions against calls placed to residential numbers. This issue becomes even more acute if it is a cell phone number.

This is not a hypothetical risk, either. There is a notorious, New York-based litigator who has filed over 20 TCPA lawsuits as a class-action plaintiff. He is known for listing his residential phone number publicly as a business number and has officially petitioned the FCC to define what a residential telephone line is in an effort to narrow the scope of the TCPA’s Business to Business (B2B) exemption.

Recently, a plaintiff filed a lawsuit alleging that the defendant violated the TCPA by calling him at a phone number that he uses for both business and personal purposes. The defendant moved for summary judgment and presented evidence that the number was used for business purposes. The plaintiff even admitted that he used the number for his business but also claimed that he used it as a personal phone. That claim was enough for the court to side with the plaintiff.

So how can an honest telemarketer protect themselves from the dual-purpose bait-and-switch? Get a compliance plan. In particular, you should scrub your calling lists for litigators, as they are among the most frequent perpetrators of the dual-purpose trick. Nothing is 100% foolproof but a good suite of TCPA and DNC compliance solutions will significantly eliminate your exposure to risk.