asterisk users - Dec 2015 - after upgrade buttons on Dahdi phones don't work

I upgraded my system from Fedora 20 to 23, and in the process from asterisk
11.3 to 13.1 . After some fiddling (recompiling Dahdi, installing extra
packages such as asterisk-dahdi and asterisk-sip), everything mostly works,
except the buttons on the Dahdi phones. Calls can be initiated from the SIP
phones, but on the Dahdi phones, the first numeric button press generates a
fast busy. Inbound calls to the Dahdi phones work just fine.

Any ideas on where I should look to fix this?

I am using a Digium TDM410 PCI card.

Thanks,
--Greg
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.digium.com/pipermail/asterisk-users/attachments/20151204/f75c8b99/attachment.html>