The Standby and Talk Time estimates given by the phone or battery's manufacture are exclusive of each other. Standby OR number of minutes Talk Time. There are many factors that will effect your battery's standby and talk time. Temperature Amount of Use Battery Capacity Capacity changes over product lifetime depending on usage. Temperature - both high and low temperatures decrease capacity.
Battery power is diminished when unused for extended periods.
Charger Performance Chargers can perform differently at different temperatures. My battery keeps going dead. The battery may not have been conditioned properly. Some new batteries need to be fully drained and fully charged three times when they are new and then once every month after that. The drain can be done during normal use of the phone.