25 Jan
2008
25 Jan
'08
5:42 a.m.
In article <20080125093035.GH17698@hezmatt.org>, Matt Palmer <mpalmer@hezmatt.org> writes
Tunnels all over the place seems like the only way it'd even be halfway practical. It's more-or-less how phone number portability works anyway, from what (little) I know.
I don't know about the USA, but in the UK it's done with something similar to DNS. The telephone system looks up the first N digits of the number to determine the operator it was first issued to. And places a query to them. That either causes the call to be accepted and routed, or they get an answer back saying "sorry, that number has been ported to operator FOO-TEL, go ask them instead". -- Roland Perry