Engagement should be focussed entirely on your customers. It should respect how they'd like to be engaged, it should follow their preferred channel of interaction, easy to access when needed and out of sight when not.
use their mobile phones to research products online before making a purchase in store according to Forbes.
consider their mobile phone to be “very important” to in-store shopping according to a survey conducted by Squareup.
consult the web upon arrival at a retail store to check whether they’re eligible for exclusive offers according to Raydiant.