http://forum.voxilla.com/ipkall-support-forum/ipkall-direct-ata-calling-not-working-anymore-15126.html
http://faq.sipbroker.com/tiki-index.php?page=Inbound+Calls+Directly+to+your+LinkSys+or+Sipura
http://www.dslreports.com/forum/r22966629-Does-IPKall-direct-to-ATA-make-a-difference