Skype for Business on Prem using teams auto attendant - Call flow?

I am trying to understand the call flow when a Skype for Business implementation (all on prem) uses a teams auto attendant.  This is what I know

auto attendant number = +1-555-555-1234

555-555-1234 routed from PSTN across SIP trunk to on prem Skype for business

Skype for Business sends the call to teams over the internet to connect with an auto attendant.

Auto attendant plays a call tree recording and disconnects

User can press DTMF selection to be "sent" to a number on premises.

This is where  I get confused...

The call flow is configured to use "user in organization" that is essentially another number that is routed over our SIP trunk.

Does Teams proxy a call that comes back over the SIP trunk to terminate in a call queue in Skype for Business on Prem?

There is no known integration configured between teams and skype for business.