Along the same lines as #1 is the example of the Brazilian government suspending WhatsApp nationally because they were technically unable to provide user chat messages for use in a police investigation.

AFAIK, most messages (90%+) are only stored in ram for a short amount of time.

source: erlang factory talk from 2015 I think...

>In the UAE, where VoIP is illegal, the government was not able to selectively block voice traffic since it is indistinguishable from text traffic. So they had to ask WhatsApp to block voice functionality whenever a user is in the UAE.

Authorities can selectively block WhatsApp voice calls, it's been done in Oman where I used to live. If I leave Oman and use WhatsApp in an uncensored country, voice calls work just fine.

This is not the case where WhatsApp is registered via a UAE number; the blocks persist no matter where you connect from.

> Authorities can selectively block WhatsApp voice calls, it's been done in Oman where I used to live.

But they cannot do it without WhatsApp's help. My understanding is that WhatsApp will check the following at the server side:

1) User IP in UAE/Oman/etc.? Block voice.

2) User's number registered in UAE/Oman/etc.? Block voice.

This is different from UAE/Oman blocking voice traffic without coordination with WhatsApp.

They don't need WhatsApp's help to do it. WhatsApp voice calls are done over different ports, so only these need to be blocked.

The UAE (and Saudi Arabia) went through the extra step of asking WhatsApp to perform a block server side because of legal regulatory issues. Oman has made no such demand.

My family regularly makes WhatsApp calls to me from Oman; they just have to switch on a VPN to tunnel out of Oman's censorware.

urm, are you really sure about 2.?

i switched SIMcards recently (the number was migrated to the new card though) and flashed another ROM on my phone. It helpfully offered me to restore all messages and media from the server. (6+ months of history)

Sure it could use the IMEI for the encryption. But i'm unsure if it can access that datapoint from application context?

/edit: i just scrolled back to the first message i've got on my most messaged contact. its from 2014. i've switched devices and sim cards since then. The phone number is the only thing that stayed the same.

WhatsApp has an optional auto-backup feature that periodically backs up your messages to Google Drive (iCloud on iOS?). You can find it under Settings > Chats > Chat backup. It is an extremely smart way to allow users to backup their messages if needed, while also ensuring that WhatsApp doesn't have access to the backups.

Once you activate a new phone, it will ask if you want to restore your messages from the latest backup. I guess it's using your Play Store account credentials to tie your SIM cards and phones together.