Detect original DID from a busy call forwarding roll-over?

Let’s say I have 3 POTS lines A, B, and C. A and B both have busy call forwarding and will roll over to line C.

If a call comes through on line C, is it possible to detect the original DID? I’d like to check if the caller dialed the number for line A or B (or even directly dialed C) so that the following behavior is executed:

If A is busy: -> roll-over to C, ring group alpha If B is busy: -> roll-over to C, go directly to voicemail box 101

No, not on a POTS line the DID will always be the pseudoDID defined in your from-dahdi/zaptel setup that the call lands on.

(Well almost always)

That was my suspicion. Thanks for the reply!