After completing the "Intensive Care" mission, the game tells you to head to your apartment and take a nap. When you wake up, your phone says that you have a voicemail from "Not Ping" but the voicemail doesn't even start as you're interrupted by a text message from Ricky telling you to meet him at Sonny Wu.
I replayed the "Intensive Care" mission but the same thing happens. Glitch....? I'm really curious, now.