Telco routing process

[rhofland at fastdial.net (Randall Hofland)]

Does anyone have a good source for information on the process that
Telcos use in their local switching offices for routing the carrier
traffic from the POTS lines used by dialup modems to the long distance
carrier backbones? And perhaps why UDP or other port traffic such as FTP
might be specifically blocked or impaired?

Thanks.

-
Subcription/unsubscription/info requests: send e-mail with
"subscribe", "unsubscribe", or "info" on the first line of the
message body to discuss-request at blu.org (Subject line is ignored).