Programmatically reversing numerical line identity presented at a communications services gateway into named IP Telephony users with “prior association”, delivers dynamic “reverse address resolution” switching connections from ground to cloud, permitting any conventional telephone to dial and connect to any associated IP Telephony endpoint in the world, without changes to the conventional telephone. Reversing line identity into associated named users bridges both the addressability and economic divide between mass conventional “paying” (mobile and fixed) and “free”. IP Telephony networks. A system for supporting communications between a user on an IP-addressed-communications-device and a telephony subscriber device, the telephony subscriber device having a corresponding telephone number, includes: one or more service nodes configured to: receive from the user the telephone number of the telephony subscriber device and create an association from the telephone number to the user, wherein the association allows the telephony subscriber device to connect to the user.