Emergency Responder does support the headless version of CSA. It supports the same version of CSA that runs on Call Manager. Check the version & policy of CSA against the specific version of ER you are running for compatibility.
The version information can be found in the ER release notes for your specific version on Cisco.com at:
http://www.cisco.com/en/US/partner/products/sw/voicesw/ps842/prod_release_notes_list.html
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