Hi @markokjan ,

Try using the earphones with the microphone attachment on a call and check that you can be heard properly.

If so then there is a problem with the phone's internal microphone or perhaps the voice inlet hole at the bottom of the phone is partially blocked with lint or dust.

Use a bright light and a magnifying glass to check that the voice inlet hole at the bottom of the phone is not blocked with lint or dust.

If it appears to be blocked DO NOT use a pin or probe to try and clear it as you might damage the microphone which is directly behind the hole.

Try a vacuum cleaner, using short sharp bursts to see if this clears the obstruction.

If it appears not to be blocked and it is OK when using the earphones with the microphone attachment then there may be a problem with the microphone itself.

If you cannot be heard properly when using the earphones with the microphone attachment either then there is a problem with the voice transmission circuitry in the phone.