If you wish to send the URL to start the call in some other fashion than the SMS or email functionality that SightCall provides, you may instead want to generate a URL in the console directly, which you can then copy and paste into some other chat app you might have on your computer.
In order to be able to use this functionality in the console, you will have to make sure that the usecase you are using has the URL code option enabled.
Navigate to https://admin.sightcall.com/usecases and click on the usecase you would like to modify.
On the first page (Setup) under the usecase name you can select the Code option "URL" :
When you are ready to start the call, you can select the appropriate usecase, and set the "Notification" to URL:
After clicking on "Generate URL", you will have to click on the CODE generated at the top to view the URL that was generated, you can then copy and paste it into some messaging app to send to a guest.