Read test for all ext

As per the below link:

https://community.ringcentral.com/questions/8229/read-sms-on-various-account.html

"You cannot read SMS messages of other extensions even if you logged in with an admin user. "

To read SMS messages of all extensions under an account you need to call Read all extensions info (/restapi/v1.0/account/~/extension) as admin user to get extension id and then use those extension ids to read messages from message store.