Join Date: Feb 1999
Location: San Jose, California, USA
Programs: AS 100K, UA MM, AA MM, IC Plat Amb, Marriott Gold, Hilton Gold, Hyatt Explorist
Posts: 3,146
My personal experience with WhatsApp on my Google Voice number is that I must reverify my WhatsApp (via SMS) whenever I move my WhatsApp app from one phone to another but not when I change from one SIM to another.
I ported my main mobile phone number to Google Voice about two years ago so that I can use it (and WhatsApp) wherever I am with whatever SIM I am using at the time. It was a godsend when I lost my phone on a trip to Indonesia earlier this year. I installed WhatsApp on my backup phone, reverified via SMS to my Google Voice number, and WhatsApp downloaded my backed-up chat history onto my phone.
Nobody knew I had lost my phone until I told them. If I had been using my USA SIM for WhatsApp, I would have been out of luck until I got home.