Long-distance entanglement distribution is a vital capability for quantum technologies. An outstanding practical milestone towards this aim is the identification of a suitable matter-photon interface that possesses, simultaneously, long coherence lifetimes and efficient telecommunication-band optical access. In this work we report upon the T center, a silicon defect with long-lived spins and spin-selective bound exciton optical transitions at 1326 nm in the telecommunications O-band. In this first study of T centers in 28Si, we present the temperature dependence of the zero-phonon line, report ensemble zero-phonon linewidths as narrow as 33(2) MHz, and elucidate the excited state spectrum of the bound exciton. Magnetophotoluminescence, in conjunction with magnetic resonance, is used to observe twelve distinct orientational subsets of the T center, which are independently addressable due to the anisotropic g factor of the bound exciton’s hole spin. Here we show that the T center in 28Si offers electron and nuclear spin lifetimes beyond a millisecond and second, respectively, as well as optical lifetimes of 0.94(1) μs and a Debye-Waller factor of 0.23(1). This work represents a significant step towards coherent photonic interconnects between long-lived silicon spins, spin-entangled telecom single-photon emitters, and spin-dependent silicon-integrated photonic nonlinearities for future global quantum technologies.