Retailers reported that sales via smartphones grew an average of 87% in 2014.
(Source: Forrester, 2015 report)

71% of in–store shoppers who use smartphones for research say their device has become more important to their in-store experience.
(Source: Google)

59% of consumers have received an advertising message on their smartphone from a brand or retailer related to their current location. 84% of these consumers said they are somewhat, very, or extremely likely to respond to these types of offers.
(Source: Stratecast)

23% of shoppers using a mobile phone in–store use a social network. More than half of them use the social network for product or brand discovery or for peer feedback on purchases, rather than for socializing.
(Source: Millward Brown Digital)

More statistics relevant to customer service can be found in Statistics, under the Resources section.

For more thoughts on mobile customer service, read the latest issue of The Edge of Service, Issue 15: Getting Mobile Customer Service Right.