Cloud version: Anyone able to create an phone field that invokes phone application?

[crmclients]

Critical need client is in Sales - need to bring Lead fields over to Opportunity but there is nowhere to land
FYI Cloud version so I cant use backend...

[crmclients]

Client is in sales so critical need

[crmclients]

Cloud version: no back in access no extensions allowed, anyone find a way to do this?
Have a client converting Leads to Opp and needs the email...