[Freeswitch-users] busy signal sent but invalid message playing

I am using freeswitch 1.4.26 with twilio sip trunking. I am using limit to limit the number of sessions: <action application="limit" data="hash orgCount org 10 !USER_BUSY" /> freeswitch seems to handle it properly and sends busy code back to twilio. Twilio logs show the call as busy. However, the message the user hears is invalid number. Is this a twilio issue or am I supposed to be handling things differently? Thanks in advance,