A quick rule of thumb for technology in ads:
If the advertisement or sign is going to be up for over a year, don’t show the technology. If it’ll be up for a year or less, go for it.
Technology changes rapidly and your advertisements and signage can look really out of date quickly. If it’s something that’s going to be up for a year or more, use words vs. pictures/graphics.
Also consider what you’re really trying to communicate. For example, the photo above was taken at my gym. People continually use their cell phones to listen to music and trainers regularly use their cell phone to video a client to help coach with form. Did the gym mean we couldn’t do this? I don’t think so; I’m thinking they actually mean no talking on your cell phone while working out.