If I remember correctly that is actually the DSL Phone line NOT the CAT5. They came with AT&T/2Wire branded DSL modem's.
But a CAT5 cable does not cost that much and you can get them almost anywhere anymore. You do not have to order though the web for something like that you can even get them at Wal-Mart for next to nothing,less than $10, and not have to pay shipping and such like with Amazon and then have to wait for delivery.