What to check

In the handset disconnect the speaker from the circuit board and measure the resistance across the speaker terminals. The reading should be either 8 or 45 ohms (check the impedance value printed on the speaker). A closed or open circuit reading indicates the speaker has failed.

If there is a door release fitted on the system you can test the handset speaker. With the telephone cover removed, disconnect the wire connected to the 'L' terminal temporarily and then, momentarily, link a wire between the 'L' terminal and terminal '1' if the speaker is working this should produce a loud buzz in the earphone.

Corrective Action

Replace the handset

Additional notes

The earphone speaker is for incoming speech and on 200 series phones the speaker ringing. Older model phones are fitted with buzzers.

The wire connected to the 'L' terminal is incoming speech from the door panel.

Links

https://www.entryphone.co.uk/shop/productdetail/200-HS