Check out the last post in the dslreports.com thread mentioned above (also linked here: http://www.dslreports.com/forum/remark,19182875 ). If you want a 2nd dial tone immediately after dialing *67 but have the ATA send the dial string (including the *67) to the server, this is the way to program the ATA.

Tim--you might consider reconfiguring your default provisioning file to include *67 and other appropriate * codes (those that require entering another number, such as call forwarding) into the field mentioned there.