An additional 17% said they didn't know or were unsure about their site's current status, revealing that as many as two-thirds of these merchants may be putting up roadblocks to the growing number of mobile consumers.

“The mobile consumer is knocking at the small merchant's door,” said Craig Tieken, director of product at TransFirst, a Hauppauge, N.Y.-based provider of transaction processing services and payment enabling technologies.

Tieken added, “Business owners who aren't already up to speed with mobile payment acceptance need to have a viable plan of action to get there.”

The research also showed that 10% of respondents to last year's benchmark Mobile Payment Acceptance Survey said they were using a smartphone or tablet to accept face-to-face credit card payments. In less than one year's time, that number has almost doubled to 17%.

The survey was sent to those businesses classified by credit card brands as “Level 4,” which are merchants that process fewer than 20,000 ecommerce or one million physical card transactions annually, according to ControlScan, an Atlanta-based payment and compliance service provider, and TransFirst.

The firms said these typically small to mid-sized businesses represent service areas such as retail and consumer goods, healthcare and human services, personal and professional services, and restaurant and hospitality. Three-quarters of survey respondents' businesses had 10 or fewer employees.