The tweet was quickly deleted, but, as with everything on the internet, there's no taking it back. According to USA Today, the tweet originally said "@ID_AA_Carmack Do you have a sec to talk? My cell is ____." This was apparently a direct message aimed at Oculus VR CTO John Carmack. Carmack is most famous for founding id Software and as the lead programmer for the video games "Wolfenstein 3D," "Doom" and "Quake." Oculus is currently owned by Facebook. That said, Carmack does have history in the aerospace industry.
I thought it odd that Business Insider missed the relevant fact that I spent over a decade building rockets, and founded the Commercial Spaceflight Federation alongside @elonmusk (I sent current contact info to your Tesla office) https://t.co/QerrJzg4EM— John Carmack (@ID_AA_Carmack) December 20, 2017
We're not going to post Musk's number here, but if you're really curious some quick internet sleuthing should provide the answer you need. Calling the number garners no response, but his voicemail message apparently quotes an easter egg from the video game "God of War."