I have used this app for video calling. I have faced so many problems with this app. Main thing is sound quality. I used this app with a 4g speed airtel internet. Even used with 4g speed internet sound quality is not good. Sometimes call was automatically dropping. Another thing is in imo app some ads are showing bottom of the screen, that irritate me.Next is regarding video quality. Video quality is not good. My mobile camera is 8 mp. But on video calling in imo my picture is not clear. I am not satisfied with IMO App. This is my personal experiance.