Metroliner telephone article 4128

For trunk (switch-to-switch) capacity, that's true, but for "services", it's totally false. The line cards in a particular CO either offer a hardware service like Caller ID or Touch Tone or they don't. To make services like that "available" in that exchange, they have to go upgrade all the line cards, whether the services are used or not on individual lines. It's cheaper to do that than keep track of which cards support what, and once new cards come out, you can't buy the older cards anyways, so all new lines will require those higher-priced cards anyways.

For software services, those are licensed by the switch vendors on a per-CO basis, so again things like Call Waiting require the telco to pay the license fee to make the service "available" in a given exchange regardless of whether anyone orders it (and such things require 6-12 months planning, so you can't just wait until someone orders it to upgrade). And, due to the way volume pricing works, a telco typically must upgrade all of their COs to the new software, even if a particular feature is only in use on one line in one exchange. Also, such upgrades tend to be for all services the vendor offers, so even if they just want 3-way calling, they have to pay for the caller ID, call waiting, etc. licenses.

In the early days I wouldn't be surprised if the telcos had used a front-end box to convert DTMF from the customer into pulse to the switch, but once you reach a critical mbutt, you need it integrated directly into the switch, which means wholesale hardware and software upgrades. The cost of doing one-offs is hideous when you consider the extra equipment cost, extra labor (at union rates), etc. Everything about Bell's procedures is aimed at making every line the same, no matter what. That's why DSL has thrown them for such a loop...

S

-- Stephen Sprunk "God does not play dice." --Albert Einstein CCIE #3723 "God is an inveterate gambler, and He throws the K5SSS dice at every possible opportunity." --Stephen Hawking

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