It's the IVR that takes commands like '1' and '6' and responds to them, so there's no such thing as ***1 and ***6 without going through the IVR.
*** is routed to the IVR by the {***:aa2} OutboundCallRoute rule. Any additional digits that were dialed (like 1 or 6) are immediately picked up from the DTMF buffer and processed before the IVR gets to its Main Menu dialog.
If Speed Dials had been implemented by simply stuffing their contents into the DTMF buffer as if they had come from the PHONE Port, then things like Star Codes and IVR commands would work from Speed Dials. But that's not how it was done, so they don't.