Since this is my first experience with Asterisk 1.8 I don’t know if it’s an Asterisk or Distro error except that I know that you recompiled Asterisk to support the new fax module and the TCP registration behaviour got worse with the newest version of the distro.
I currently register my iPhone on TCP with Asterisk. When I set the extension transport to “TCP only” the phone registers but Asterisk does not increment the registration count. Sip show peers does not show the extension as registered and calls from the phone fail with error 503 (wrong transport).
If I change the transport to UDP the phone registers fine.