integrated messaging does what?
Not sure what you mean. Do you mean Verizon Messages? This is a messaging app used to send/receive SMS/MMS messages from other cellular users.
It also give you the ability to view/send/receive messages to/from your line on other devices such as tablets and computers.
Messages sent from one device would show up on all devices logged in under the same line. Messages sent to that line would be viewable on all devices logged in under the same line.