Actually, they are building on existing ones, they extend GNU SIP Witch: http://www.gnutelephony.org/index.php/GNU_SIP_Witch http://www.gnutelephony.org/index.

Actually, they are building on existing ones, they extend GNU SIP Witch: http://www.gnutelephony.org/index.php/GNU_SIP_Witch http://www.gnutelephony.org/index.php/GNU_SIP_Witch