First of all, you should be aware of if the publisher doesn't allow to display its content in Iframe, you will not be able to show it inside SharePoint.
Otherwise, you will be able to open an External URL using SP.UI.ModalDialog SharePoint Modal Dialog.
Please, check the details at Open a link via Modal Dialog in SharePoint
In case, you would like to use Jquery, so you can use Fancy box as Iframe, I think this link may help you to Use JQuery to show Modal Popup Per Session In SharePoint
Jquery
Fancy box
1.1k questions
673 answers
454 comments
193k users
Related Activities
Categories
Most popular tags