not generating dtmf tones

Hello pauljdavies,

Thanks for reaching out in the Apple Support Communities!

To help resolve this issue, make sure you have the ringer enabled on your iPhone. You can check the Ring/Silent switch on the left side of your iPhone as outlined here:

Use the side, Home, and other buttons on your iPhone

Ring/Silent

Use the ring/silent switch to mute sounds and alerts.

If the switch shows orange, it means your iPhone is in silent mode and will vibrate for incoming calls or alerts. When in silent mode, the alarms you set in the Clock app will still sound, and calls from Favorite contacts will still ring.

If your ringer is enabled, make sure the volume is turned up:

Volume up/down

Use the volume up/down buttons to adjust the volume when listening to music, watching videos, or playing games.

When you press the buttons, you'll see the Volume under the indicator. When you're not using other apps, the buttons will adjust the ringer volume and you'll see Ringer under the indicator.

Best regards.