Hi Christine,
Unless I'm misunderstanding, you don't need to check SIP Headers to get that info.
It might depend a little on how your DIDs are set, but if it's a 1 for 1 in regards to the numbers the customers dial, you should be able to get that using Architect's built-in variables. (https://help.mypurecloud.com/articles/architect-default-variables/)
More specifically, you can get that using the system variable: Call.CalledAddressOriginal
You can then just compare the value on it to DNIS 1 and 2, and if it's a match you can increase the priority using the "Transfer to ACD" component (there is an attribute in there to set the priority).
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Marcello Jabur
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