Ooma Telo Headset Cordless Phone Battery Ni-MH, Volt, 700 mAh - Ultra Hi-Capacity - Replacement for OOMA HB1001 Rechargeable Battery Replacement Battery for OOMA HB1001 - Ni-MH, Volt, 700 mAh. 100% compatible with your OEM battery - 3 year warranty. Made with high quality Japanese cells. Synergy Digital is a Registered Trademark