Section 51.309 - Use of unbundled network elements(a) Except as provided in § 51.318 , an incumbent LEC shall not impose limitations, restrictions, or requirements on requests for, or the use of, unbundled network elements for the service a requesting telecommunications carrier seeks to offer.(b) A requesting telecommunications carrier may not access an unbundled network element for the exclusive provision of mobile wireless services or interexchange services.(c) A telecommunications carrier purchasing access to an unbundled network facility is entitled to exclusive use of that facility for a period of time, or when purchasing access to a feature, function, or capability of a facility, a telecommunications carrier is entitled to use of that feature, function, or capability for a period of time. A telecommunications carrier's purchase of access to an unbundled network element does not relieve the incumbent LEC of the duty to maintain, repair, or replace the unbundled network element.(d) A requesting telecommunications carrier that accesses and uses an unbundled network element consistent with paragraph (b) of this section may provide any telecommunications services over the same unbundled network element.(e) Except as provided in § 51.318 , an incumbent LEC shall permit a requesting telecommunications carrier to commingle an unbundled network element or a combination of unbundled network elements with wholesale services obtained from an incumbent LEC.(f) Upon request, an incumbent LEC shall perform the functions necessary to commingle an unbundled network element or a combination of unbundled network elements with one or more facilities or services that a requesting telecommunications carrier has obtained at wholesale from an incumbent LEC.(g) An incumbent LEC shall not deny access to an unbundled network element or a combination of unbundled network elements on the grounds that one or more of the elements: (1) Is connected to, attached to, linked to, or combined with, a facility or service obtained from an incumbent LEC; or(2) Shares part of the incumbent LEC's network with access services or inputs for mobile wireless services and/or interexchange services.61 FR 45619, Aug. 29, 1996, as amended at 68 FR 52294 , Sept. 2, 2003; 70 FR 8952 , Feb. 24, 2005