[Asterisk-Users] Problem with TDM400P and cidstart=polarity

[Rickard Kristiansson]

I'm testing a TDM400P with FXO module to receive incoming calls from an 
analogue line and send it to a SIP device.
To recieve callerid, I need to use cidsignalling=dtmf and cidstart=polarity.
The problem is that when a call is finished, the TDM400P seems to require 
about 20 seconds to prepare for the next incoming call. If a new call comes 
in within 20 seconds after the previous call was hungup, the TDM400P answers 
with a modem carrier, sounding like you're calling a modem pool..!  The 
caller hangs up and retries the call, and the next time everything is OK. 
If the second call comes in later than 20 seconds after the previous call 
was finished, or if I remove the cidstart=polarity (and don't get callerid) 
everything works fine.
I can't see any difference in the Asterisk debug logs worth mentioning... 
Has anyone experienced anything similar..?