First of all, the IVR server cant send media to the From header in a SIP INVITE. Media is sent to the IP address in the connection info header in the SDP of either your INVITE or your response. This is what the connection info looks like
c=IN IP4 10.1.6.17
So something is not right in that statement.
Secondly, you can influence which cucm server is used to make outbound calls ie (the from header) based on a few factors..
1. Enable run on all active nodes in your cucm sip trunk
2. Enable run on all active cucm nodes on the route list..
With these two enabled, this will ensure that the cucm that is used to send the call out the trunk is not going to be the one on the route group of the sip trunk or route list but the one that the device making the call is registered to. So if phone A from location A registered to cucm1 makes a call, the from header will show cucm1.
You can refer to this document which details the process of selecting a cucm node that will be used for outbound calls on a sip trunk
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