You will not be able to ring old rotary phone with DC power, you will need specific low frequency AC power ~40-70v AC of 25-30Hz.
Sample circuit for this purpose can be found here in this post. However please note that this circuit is far away from optimal, it was designed based on old components which were found lying around.
Frequency might need to be adjusted with 210k resistor and/or 220nF capacitor. According to information from other articles frequency has to be 25Hz, but I found that it may vary. Transformed was taken from old legendary Nokia 3310 charger (AC 230v to DC 3.7v).
This circuit gives ~110v with no load (CAUTION HIGH VOLTAGE), please be sure what are you doing.
- Stand by current 50mAh
- Max current of this circuit is ~200mAh on short
- When phone is ringing voltage drops to ~50v current 150mAh
Video how it works:
Source articles:
https://www.youtube.com/watch?v=qojn_-mxrGk
https://www.circuit-diagram.org/circuits/755bbcda01f94aec8090b0f452611406
https://www.hackatronic.com/12v-to-230v-inverter-circuit-diagram/
https://inverter-circuit.com/12vdc-to-220vac-inverter-with-555-timer.html