  Quantum memories for light will be essential elements in future long-range
quantum communication networks. These memories operate by reversibly mapping
the quantum state of light onto the quantum transitions of a material system.
For networks, the quantum coherence times of these transitions must be long
compared to the network transmission times, approximately 100 ms for a global
communication network. Due to a lack of a suitable storage material, a quantum
memory that operates in the 1550 nm optical fiber communication band with a
storage time greater than 1 us has not been demonstrated. Here we describe the
spin dynamics of $^{167}$Er$^{3+}:$Y$_{2}$SiO$_{5}$ in a high magnetic field
and demonstrate that this material has the characteristics for a practical
quantum memory in the 1550 nm communication band. We observe a hyperfine
coherence time of 1.3 seconds. Further, we demonstrate efficient optical
pumping of the entire ensemble into a single hyperfine state, the first such
demonstration in a rare-earth system and a requirement for broadband spin-wave
storage. With an absorption of 70 dB/cm at 1538 nm and $\Lambda$-transitions
enabling spin-wave storage, this material is the first candidate identified for
an efficient, broadband quantum memory at telecommunication wavelengths.
