Topdogkaine,
Are you using SIP Trunks or POTS lines?
If it is SIP Trunks then you may be using the wrong DTMF Decoding Payload which will result in no DTMF.
If it is POTS lines it may be that the Hybrid Balance circuit is not calibrated correctly.
The other issue is that all of your DTMF resources are in use or going bad.
How many devices do you have on your system?
Do you have a PEC or PS-1 or both?
Thanks,
TE