I would not contact your carrier first unless it really is only an issue with phone calls. They can/will only address the issue if it's something at their end.
If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker, read this support article --> If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker - Apple Support
We had the speakers fail on one of our devices. Nothing to do about it but get it repaired. If you cannot track down the issue yourself, get Apple to take a look.
How to make a Genius Bar appointment
1. Go to Genius Bar Reservation and Apple Support Options - Apple
2. Go to "Get hardware help".
3. Select your hardware and continue selecting options requiring replacing parts until you see "Bring in for Repair"
4. Sign in with your Apple ID
or:
Refer to this document for ways to contact Apple ➞ Choose your country or region - Official Apple Support
Select your country (also look for "other" regions), then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.
or:
Contact Apple for support and service by telephone ➞ Contact Apple for support and service - Apple Support
Incidentally, if you have headphones of some kind, do you hear sound through them? Are you using Bluetooth audio devices such as hearing aids? Those can disable sound from a device.