How can we change sms message read status

Since I am new to the ringCentral apis.. I was exploring the sms api.

I was successful to send the sms. But what stuck me is the sms message status.

The below is the part of the response I got:

{
"type": "SMS",  "creationTime": "2019-11-10T18:50:02.000Z",  "readStatus": "Read",  "priority": "Normal",  "attachments": [    {      "id": ***********,
}

Here "readStatus": "Read"

While going through the api documentation I found the readStatus can be 2 types:

Read, Unread

My first question is what does this read status means?

How can I change it and mark it as Unread again? Is that possible?