Hi Brian, I have Aastra 55i, it does have STUN and Rport support, and I like its rport support. On web interface, under network settings->Advanced Network Settings->Rport (RFC 3581)Enabled for Rport
or

STUN Server
STUN Port

for STUN support, however I like rport better, which I can have call forwarding working seamlessly for freeswitch in public ip address, even my Aastra is behind my doule-NATed home network.

Best regards,
Chris