How to use Shortcuts on my iPhone to call in to conferences?

I did something similar that works for me. In my case, there's an optional attendee ID as well. The conference number I'm showing here is 1-555-555-5555

1. Ask "Meeting access code" (Input type = Number)
2. Set variable {ConfNum} to {Provided Input}
3. Ask Attendee ID (Input type = Number, default = 0)
4. If Provided Input is 0
5. Text 1555-555-5555,,{ConfNum}#,#
6. Otherwise
7. Text 1555-555-5555,,{ConfNum}#,{Provided Input}#
8. End If
9. Call {If Result}

Also note that if you use a semicolon (;) instead of a comma (,) for the pause, it will wait until you press a button to dial the remaining string.