[Freeswitch-users] TCP ACK Ping

Hello all, I have been doing some experimentation migrating several phones from UDP to TCP SIP to address MTU issues with BLF NOTIFYs. Mostly everything is working great except for Polycom handsets running UC v4. (Note that I did not test any v3 phones.) The phones are behind NAT and Freeswitch is on a public IP. The phones periodically send a TCP ACK ping to Freeswitch which goes unanswered and then phone then tears down the TCP connection. I'm not at all a TCP expert but should Freeswitch be responding to this unsolicited ACK? I have tried in vain to disable these keepalives from the Polycoms. Has anyone else encountered this behavior? Thanks in advance, Spencer