This reference is fed to the base of T6 to keep the �VREG+� line at 2.65V.
8.1.13. BATTERY CHARGING CIRCUIT (SEE Fig. 27)
The supply for the battery comes from the charge terminals at J3 and J4. Battery charge rate is controlled by switching the current through T7 such that the average charging current is 180mA. The current flow is monitored at pin 49 of the BBIC by measuring the voltage across R56. D21 protects against the high voltage present on the charge contacts (J3 and J4) when there is no battery in the handset. R42 and C50 provide a signal to the BBIC (pin 27) to detect that the handset has been placed on the base charger.