Power supply circuit and telephone system

The embodiment of the invention provides a power supply circuit and a telephone system, so as to solve the problem of high energy consumption of the existing telephone system which is powered by a single-path power supply type telephone line. The power supply circuit comprises a control circuit, a switching circuit, a charging/discharging circuit, a primary charging and clamping circuit, and a secondary charging and clamping circuit, wherein the control circuit is used for outputting a control signal according to a voltage output by the primary charging and clamping circuit and a preset voltage; the switching circuit is used for switching between on and off according to the control signal output by the control circuit; the charging/discharging circuit is used for acquiring energy through the switching circuit and storing the energy when the switching circuit is switched on, and inputting energy to the primary charging and clamping circuit and the secondary charging and clamping circuit respectively by releasing the stored energy when the switching circuit is switched off; the primary charging and clamping circuit is used for outputting a voltage signal; the secondary charging and clamping circuit is used for outputting at least one voltage signal; and the voltage output by the primary charging and clamping circuit does not equal the voltage output by the secondary charging and clamping circuit when the power supply circuit is in a steady state.