On 04/18/2010 03:37 AM, anorexicpoodle wrote:
Though this topic does raise a question I have been kicking around for a while, has anyone here tried implementing a SIP equivalent of URPF on your border controllers or proxies on the peering side, so if you cannot determine a route back to the calling number you drop the call to IVR or reject? Obviously implementing UPRF at L3 has saved me tons of headaches in other facets, but certainly a L5 solution could alleviate a potential ton of spam calls that come through normal PSTN connections. Thoughts?
This would seem to come down to the question of what exactly it means to have or not have a route to a given calling number. Validate it against basic NANPA form rules? Look it up prefix-wise against a current list of currently allocated NANPA and Pooling blocks, or against the LERG? See if at least one of your termination carriers has a specific route of a certain minimum prefix length (i.e. longer than just "1")? -- Alex Balashov - Principal Evariste Systems LLC 1170 Peachtree Street 12th Floor, Suite 1200 Atlanta, GA 30309 Tel: +1-678-954-0670 Fax: +1-404-961-1892 Web: http://www.evaristesys.com/