Found this out during a session with @defcomllc
D phones won’t accept SSL Method Default and phones will fail with errors like EISSUER_MISMATCH
EUNTRUSTED
We set the SSL Method tlsv1_2 and phone provisioned nicely; S-phones did not complain about this change either.
Updated https://wiki.freepbx.org/display/PHON/TLS+and+SRTP to reflect this change.
May work with tlsv1_1 as well.
Thanks for your help debugging this @defcomllc!