47 C.F.R. § 51.100 – General duty.

(a) Each telecommunications carrier has the duty:
1. (1) To interconnect directly or indirectly with the facilities and equipment of other telecommunications carriers; and
2. (2) To not install network features, functions, or capabilities that do not comply with the guidelines and standards as provided in the Commission's rules or section 255 or 256 of the Act.
(b) A telecommunication carrier that has interconnected or gained access under sections 251(a)(1), 251(c)(2), or 251(c)(3) of the Act, may offer information services through the same arrangement, so long as it is offering telecommunications services through the same arrangement as well.