Why does it sound muffled to someone I call

Hi,

Try using the earphones with the microphone attachment.

If your voice is heard clearly on a call then there is a problem either with the phone's microphone or perhaps the voice inlet hole, found on the bottom edge of the phone is blocked with dust or lint.

To see if hole blockage may be the case, use a magnifying glass and a strong light to check if the hole is blocked. If it appears to be, DO NOT use a pin or similar to try and clear the hole. The microphone is right behind it and you may damage it. Try a vacuum cleaner using short sharp bursts and see if it clears the obstruction.

if it still appears blocked and you cannot clear it, here is a link to the Ifixit guide on how to replace the speaker in your phone. Hopefully by using this guide you will be able to access the voice inlet hole and clear it properly. It may also allow you to view the microphone as well.

ZTE Majesty Speaker Replacement

If your voice is still muffled after cleaning the voice inlet hole then there is a problem with the microphone and it need to be replaced.

If your voice is still muffled when using the earphones with the microphone attachment then there is a problem with the voice transmission circuitry in the systemboard.