Telco routing process

[ewhorne at mindspring.com (Bill Horne)]

Randall Hofland wrote:

> 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?

Calls from ISP subscribers go to modem pools leased or owned by the ISP.
Most ISPs choose to hire companies such as BBN to handle the modem pools and
then take the traffic as layer-3 (i.e., IP) data.

Local Exchange Carriers (LECs) almost never get involved in carrying packet
data, or anything other than switched circuit connections.  Any restrictions
on the port(s) you use have to happen after the modem bank, so it's very
unlikely that your LEC is blocking anything.

> Thanks.

You're welcome. HTH.

Bill Horne


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