Route all inbound calls from 1 trunk out on another trunk

Hi, I would like all calls coming into my FreePBX 13 on Trunk A to be immediately routed out to the PSTN on Trunk B. Keeping in mind that all my normal outbound routes are using Trunk C to get to the PSTN. I am struggling to get this working any help would be greatly appreciated.

Should be very straight forward:
Inbound Route (configured for trunk A) – Set Destination – Trunks and select trunk B.
You may need to do some digit manipulations on trunk B depending on provider B rules.

Thanks for the swift reply Andrew.
How to I apply an inbound route only to trunk A

Usually people are creating a Route per DID or a group of (pattern).

I know but not in this case. It’s not number specific.
I have outbound calls coming in from another phone system on Trunk A and I want to flip them all out on trunk B to the PSTN - if possible that is.

Is there a pattern match for the trunk it’s coming from??

What is an A-trunk? Is it SIP? Does it have something unique in Request URI for all the incoming calls?
The dirty trick will be using custom context but I believe it should be a better way.