Outbound Touch Tone not always working

Hi I am having issues with our phone system where the touchtone is not always working and seems to be a bit laggy. I have tried all the dtmfmode options and dtmf. Any suggestions?

What phones do you have?

Is any of your LAN wi-fi?

What kind of trunk?

We are using Cisco 7940’s and we are using Freepbx trunk. We are behind a Cisco ASA 5505. We do have Wifi but all the phones are wired.