WE have an asterisk server that we use for conference calls and seem to be having issues with DTMF not working or is a timeout issue in the extensions_custom.conf file. Calls come into a Cisco call manager using MCGP which has sip trunk built to our conference server using rfc2833. Both internal and external calls fail and get invalid ext if they wait until after the last word on the greeting now if they enter in the ext while the greeting is being played or a second after it finishes it seems to work fine. when we use tcp dump we see all the digits (4) digits but looking at the asterisk logs I only see 2 or 3 of the 4 digits. below is my config file, if any one had any ideas let me know as I’m ready to pull my hair out 
[conferences]
iitExten(,)nclude => ext-meetme; in [ext-meetme] contest are stored all the conferences created in FreePBX
exten => s,1,Answer
exten => s,n,Wait(1)
exten => s,n,Background(en/enter-conf-call-number); Insert you welcome message
exten => s,n,Goto(w,1)
exten => w,1,Wait(1)
exten => w,n(begin),Set(TIMEOUT(digit)=3)
exten => w,n,Set(TIMEOUT(response)=15)
exten => w,n,WaitExten(,)
exten => i,1,Goto(conf-inval,s,1)
exten => w,n,Playback(invalid)
exten => w,n,Goto(w,1)
[conf-meetme]
include => ext-meetme; in [ext-meetme] contest are stored all the conferences created in FreePBX
exten => s,1,Answer
exten => s,n,Wait(1)
exten => s,n,Background(medplus/conf-line); Insert you welcome message
exten => s,n,Goto(w,1)
exten => w,1,Wait(1)
exten => w,n(begin),Set(TIMEOUT(digit)=3)
exten => w,n,Set(TIMEOUT(response)=15)
exten => w,n,WaitExten(,)
exten => i,1,Goto(conf-inval,s,1)
exten => w,n,Playback(invalid)
exten => w,n,Goto(w,1)
[conf-inval]
include => ext-meetme; in [ext-meetme] contest are stored all the conferences created in FreePBX
exten => s,1,Answer
exten => s,n,Wait(1)
exten => s,n,Background(invalid); Insert you welcome message
exten => s,n,Goto(w,1)
exten => w,1,Wait(1)
exten => w,n(begin),Set(TIMEOUT(digit)=3)
exten => w,n,Set(TIMEOUT(response)=15)
exten => w,n,WaitExten(,)
exten => i,1,Goto(conf-inval,s,1)
exten => w,n,Playback(invalid)
exten => w,n,Goto(w,1)