It is usually use the selling second hand or used devices and as well as purchase also the same. I have sell some smart phones i.e. one Lenovo Mobile, Samsung galaxy on5 in this OLX site in app. Easy to sale on that site, its asking device price, model, contact number, my number shows in my add, the buyer directly contacted me and buy the device.
Next another mobile honor 4X trying to sale in OLX by using mobile app, but my mobile number not showing in my add, OLX provided chatting with others who is interested buy that. This facility is not good, while chatting is taking longer than direct dealing. Some time mobile data wasted, some time mobile data unavailable, user feel hesitate. Direct communication always save time, time more valuable than anything.