SRTP and TLS using Aastra 6757 phones and the latest Freepbx distro

I just upgraded the the latest distro yesterday (the one for v 2.10 with CentOS 5.7) and was wondering if anyone had experience getting TLS and SRTP to work specifically with Aastra phones? I have a need to open up a few over the Internet but would rather secure them rather than deploying a VPN to each location. Any help is appreciated! Thanks!