How much is a client’s cell phone number worth to you? For Mario Tricoci Salons and Day Spas, the answer is $20. A pop-up screen on the Palatine, Ill.-based chain’s website offers visitors a $20 discount as an incentive to join its Mobile Mario club. By signing up, they agree to receive up to four promotional texts per month. The incentive appears to be working: The mobile club has more than 120,000 members.

“We use this channel to cross-promote different departments within the salon and spa. It’s a key part of our marketing strategy,” says senior VP and chief marketing officer Megan Bueschel. “We state upfront that we will not text more than four times per month — not too much, but enough to keep people engaged. We‘ve seen no reluctance to signing up.”

The salon always sends an offer on the first of the month — typically a percentage or dollar amount off a related service when a basic service is booked. “In addition, some months we have an informational text about a current promotion, or anniversary or birthday offers,” she says.