You sure can. The feature is called SABR (Sourced ANI Based Routing) Source and ANI Based Routing in AOS Voice Products
The document i posted tells you how to configure it.
By default, the AOS switchboard routes calls based on the DNIS (dialed number) but by using SABR we can route calls based on the ANI (Caller number).
You would just configure SABR on the SIP trunks going to your other locations. Hope that helps.
Let me know if you have questions.
We currently do not have our other locations on our phone system, so there isn't a trunk going to them. Do you know if it is possible to send the calls back out to their outside line?
What you can do is create a virtual user, user account that doesn't have a sip phone, which just acts as an answering point. Then configure Find Me Follow Me (FMFM) and then from there you can route calls based on who is calling and send them to external numbers.
Here are some videos and config guides to help. Let me know if you have questions.
Hope that helps. Let me know if you have questions.