and later fiber optic

Frontier Communications tries a nationwide VoIP approach with Mitel
The way Frontier Communications broke into the top five local incumbent exchange providers in the U.S. (it’s been estimated as high as #4, currently it’s no lower than #6) is by acquiring copper, and later fiber optic, lines from competitors–often
Frontier Communications Introduces Commercial Cloud-Based Voice Solution
Frontier Communications launches cloud-based VoIP service
Frontier launches cloud-based VOIP service

via “frontier communications” – Google News