I don't have my phone at the moment, since I turned it over yesterday at the shop for a screen replacement. The SIM card is removed and it's sitting in my wallet now.
When I opened WhatsApp Web a couple minutes earlier today, I was connected to my account and could send and read new messages. This connection continued for around 15 minutes or so, until it stopped receiving signal from the phone.
My question is, how was WhatsApp Web able to receive signal in the first place?