(a) A LEC shall implement throughout each state in which it offers telephone exchange service intraLATA and interLATA toll dialing parity based on LATA boundaries. When a single LATA covers more than one state, the LEC shall use the implementation procedures that each state has approved for the LEC within that state's borders.
(b) A LEC shall implement toll dialing parity through a presubscription process that permits a customer to select a carrier to which all designated calls on a customer's line will be routed automatically. LECs shall allow a customer to presubscribe, at a minimum, to one telecommunications carrier for all interLATA toll calls and to presubscribe to the same or to another telecommunications carrier for all intraLATA toll calls.
(c) A LEC may not assign automatically a customer's intraLATA toll traffic to itself, to its subsidiaries or affiliates, to the customer's presubscribed interLATA or interstate toll carrier, or to any other carrier, except when, in a state that already has implemented intrastate, intraLATA toll dialing parity, the subscriber has selected the same presubscribed carrier for both intraLATA and interLATA toll calls.
(d) Notwithstanding the requirements of paragraphs (a) and (b) of this section, states may require that toll dialing parity be based on state boundaries if it deems that the provision of intrastate and interstate toll dialing parity is procompetitive and otherwise in the public interest.