How long does the internal battery last, and what ports are on the rear of the modem?

The modem includes an internal battery that provides up to 8 hours of backup power. The rear panel includes Voice 1–4 ports for analog telephones, a Cable (coaxial) port, an Ethernet (Internet) port, a Power port, a Battery slot, and an ATA port for additional voice hardware (not yet available in all markets). (Pages 2 and 8)