People can't hear me when I call from my iphone 6

Your iPhone does everything with an app, so I would start with a forced reset. Simply press and hold the home button and side (power) button until the Apple logo appears, then release and let the phone reboot. That should reload all the software and give you a clean starting point for the next steps. If the reboot fixes it all well and good.

Next step is a simple test of the microphone. Bring Siri to life and ask any question, “hey Siri what time is it?” Is good enough to get some kind of response either on screen or spoken back to you. If Siri can’t hear you have a close look at the microphone for blockage or physical obstructions (even a bad choice of phone case will do it).

If you have the original Apple ear buds test them. Try plugging in several times to exercise the switch contacts in the connector. You could also try switching between conventional handset or speakerphone (and/or Bluetooth devices like AirPods or car handsfree) to see if anything behaves differently.

Your last resort if it is still not working is Get Support (link) and arrange to get the hardware checked and serviced by Apple. At least you have the satisfaction of being able to tell them what you already tried.