Call Jay Norris on his prototype phone
"Call Jay Norris on his prototype phone" is an objective in the story mission Friend Request in Grand Theft Auto V.
Wait for Jay Norris to get through most of his speech. He will pull out the Lifeinvader phone. At this point, pull out your own cellphone and in the contacts list scroll down to his name:
After that just call him. Everything else takes care of itself after that.
Do not wait too long on making the call as he will otherwise finish his speech and get away unharmed and the mission will fail with the message "Michael failed to detonate the Phone"