I hope you get paid handsomely for this terrible idea.
To answer, have the group establish a phone line. Have the on call person actively forward to their own number. I know Verizon and AT&T can forward easily. You can have your office staff do it daily, if not, just have to suck it up and do it yourself. Or have ASC staff do it.
Maybe not the solution you’re looking for, unless you have a huge group or lots people going to ASC I think this is the simplest way to do it. Or obviously have a dedicated pager/phone for ASC on call and pass it to each other daily.
PS. I just looked, there are telecom companies who may smooth this out, obviously for a fee, on line. If you don’t want to do this yourself. Send them an on-call schedule monthly, maybe? I can’t resist to say again, it sounds terrible. We as residents use to cover some of our attendings pain patients at night. What a crock pot of s**t idea that was.