[VoiceOps] SIP - Preserving original source number in redirected call

[Calvin E.]

I'm faced with a Lawful Intercept scenario for SIP call forwarding which
requires the forwarded call to contain the original source and destination
numbers. The source number may or may not be changed on the forwarded leg.
I see how the original called number can be preserved in Diversion
or History-Info, but how do I preserve the original source number? Is there
an RFC for this that I missed, or misunderstood?

Is it as simple as using PAI for the forwarded A-number and From for the
original? I'm concerned the wrong number might appear to the called party.
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