Many believe that the messages are there like the radio or the chips and that they look like a lot of garbage on the interface in the Kiroshi, but in truth V's phone is a physical phone, in photo mode you can see it and in the game it is mentioned with the selfie with Kerry.
This phone only transmits notifications and calls like wireless headphones, but you cannot respond to text messages in seconds, so when you do, time slows down, which is not the same as pausing the game, this slowdown is not present in the car explicitly but it is when you change weapons and radio stations, so, Chum, you are not completely wrong, but the phone is physical and it is not a device integrated into the Kiroshi and it is not microscopic either, the same game in Photo mode shows that it is a medium-sized and thick one.