Want to let your customers know with a phone call or text that the items they need are ready for pickup? Think twice before you dial. Depending on the circumstances, the Telephone Consumer Protection Act, passed in 1991 and revised in 2013, may turn that quick reminder into a lawsuit.

National drugstore chain Walgreen Co. learned this the hard way when it got hit with a TCPA class action suit after calling customers to remind them that their prescriptions were ready for refill. What seemed like harmless phone calls turned into a legal headache for the company, which recently agreed to settle the case for $11 million.

In Kolinek v. Walgreen, lead plaintiff Robert Kolinek claimed that he had provided his phone number for identity verification purposes, but that starting in 2012, he had been receiving robocalls telling him he needed to refill his prescription. Kolinek found this objectionable, claiming that he and other class members did not approve the use of their phone numbers for prescription refill reminder purposes, so he filed a suit against the company under the TCPA.