You can now send one or many opt in forms via email to your clients using the PSA Contacts screen. 

If you'd like to allow your user to update their mobile phone you can check that box. The preferred way to send Opt in should be email so that you don't send SMS without the users permission. 

Users will receive an email similar to the one below: 

Once they click the Opt in link they will receive a dialog like the one below to confirm they'd like to receive SMS and they can update their phone number in ConnectWise if you've allowed them to do so. 

Once they are opted in the system will show a checkbox that they've opted in. 

This data also shows in the ConnectWise Pod. You can send an Opt in Form from inside of ConnectWise. A green checkbox shows when someone has opted in: 

To change the language in the email that is sent you can use the options above: