Hi there and welcome
Can you tell me please the make and model of the phone?
Can you remove the battery please from the phone and wait 5 minutes,
Connect the battery, turn on the phone and tell me if it then functions correctly please.
This can be the stereo port as being jammed (the switch inside)
Can you get a pair of headphones and push them into the headphone port and take it out. Repeat 10 times then try to make a call and let me know if it now works please.
Do you see a picture of headphones on the top left of the phone?
ok, it still means it thinks headphones are plugged in and this is the problem.
Use a Match and clean the inside of the port out where the headphones go, as much as possible, rub it along the insides and try to get that icon to dissapear which will resolve the issue.
Let me know the results please.
If you play music on the phone, can you hear it?
Now we have the headphone icon removed, restart the phone, make a call to someone different and tell me if with them you still have the issue please.
ok, we will have to reset the phone. This will remove all data and return the phone to new, so backup any files off the phone you wish to keep (eg: Photos)
Then go to Settings, Backup & Reset, Factory Reset.
Let this complete and when it has, setup the phone again like when you first received it.
After doing this, tell me if it then functions please.
It is the internal mainboard that has faulted. Will be the audio module for microphone and phone speaker
A corrupted firmware can cause this. But we have ruled this out by reinstalling it.
I am really sorry about this and you are going to have to return the phone to have it replaced. It will be covered by the warranty if this has not expired, and the replacement will be done at no cost to you.
I am really sorry about this, and if you have problems, or would like any additional information or assistance, please do not hesitate to let me know.
And if you can take a second to rate my service, that would be greatly appreciated.
No, as we ruled all that out via the reset, which confirms the issue as hardware, its why we did the reset.